diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8575e4bb..9ef80cc1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -99,3 +99,21 @@ jobs:
         run: bun install
       - name: Test
         run: bun test-unit
+  check-license:
+    name: Check license headers
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+      - name: Check license headers
+        run: |
+          fail=false
+          git ls-files '*.ts' '*.js' | while read file ; do
+            if ! grep -Eq "(Copyright|generated|GENERATED)" <(awk 'NR<=3' "${file}") ; then
+              echo "license header checking failed: ${file}"
+              fail=true
+            fi
+          done
+          if [[ "${fail}" == "true" ]] ; then
+            echo "Some files failed license check"
+            exit 1
+          fi
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 74bd4a51..41b3c037 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -37,6 +37,7 @@ This release marks our first release under the Prometheus umbrella.
 - AggregatorRegistry renamed to ClusterRegistry, old name deprecated
 - chore: update faceoff to 1.1
 - perf: Stat aggregation uses similar strategy to collection. 60% faster aggregation
+- chore: Add copyright license headers and test
 
 ### Added
 
diff --git a/benchmarks/cluster.js b/benchmarks/cluster.js
index d2ea4e9c..3678c6ae 100644
--- a/benchmarks/cluster.js
+++ b/benchmarks/cluster.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { getLabelCombinations, getLabelNames } = require('./utils/labels');
diff --git a/benchmarks/counter.js b/benchmarks/counter.js
index 13b326f7..5e1f6d0d 100644
--- a/benchmarks/counter.js
+++ b/benchmarks/counter.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { getLabelNames, labelCombinationFactory } = require('./utils/labels');
diff --git a/benchmarks/gauge.js b/benchmarks/gauge.js
index d4c3f4db..eddb7cae 100644
--- a/benchmarks/gauge.js
+++ b/benchmarks/gauge.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { getLabelNames, labelCombinationFactory } = require('./utils/labels');
diff --git a/benchmarks/histogram.js b/benchmarks/histogram.js
index 1ecc8f54..9e51dcfa 100644
--- a/benchmarks/histogram.js
+++ b/benchmarks/histogram.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { getLabelNames, labelCombinationFactory } = require('./utils/labels');
diff --git a/benchmarks/index.js b/benchmarks/index.js
index 666e1138..ef05209b 100644
--- a/benchmarks/index.js
+++ b/benchmarks/index.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Benchmark = require('faceoff').default;
diff --git a/benchmarks/registry.js b/benchmarks/registry.js
index d2a364de..c608fb98 100644
--- a/benchmarks/registry.js
+++ b/benchmarks/registry.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { getLabelNames, getLabelCombinations } = require('./utils/labels');
diff --git a/benchmarks/summary.js b/benchmarks/summary.js
index 69b8f3c3..2c18564d 100644
--- a/benchmarks/summary.js
+++ b/benchmarks/summary.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { getLabelNames, labelCombinationFactory } = require('./utils/labels');
diff --git a/benchmarks/util.js b/benchmarks/util.js
index 7c08e3b3..a4009e14 100644
--- a/benchmarks/util.js
+++ b/benchmarks/util.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Path = require('path');
diff --git a/benchmarks/utils/labels.js b/benchmarks/utils/labels.js
index bf0a7ef9..ff4893f1 100644
--- a/benchmarks/utils/labels.js
+++ b/benchmarks/utils/labels.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const VALUES = {
diff --git a/example/cluster.js b/example/cluster.js
index 6ea70d06..2686a27e 100644
--- a/example/cluster.js
+++ b/example/cluster.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const cluster = require('cluster');
diff --git a/example/counter.js b/example/counter.js
index 257ef2b4..9a08814c 100644
--- a/example/counter.js
+++ b/example/counter.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 // Counter
diff --git a/example/default-metrics.js b/example/default-metrics.js
index 7d2b9494..0ea2e93e 100644
--- a/example/default-metrics.js
+++ b/example/default-metrics.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { collectDefaultMetrics, register } = require('..');
diff --git a/example/exemplars.js b/example/exemplars.js
index 29f779e7..7f7127ca 100644
--- a/example/exemplars.js
+++ b/example/exemplars.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { register, Registry, Counter, Histogram } = require('..');
diff --git a/example/gauge.js b/example/gauge.js
index 3b1b1903..fb68700d 100644
--- a/example/gauge.js
+++ b/example/gauge.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 // Gauge
diff --git a/example/histogram-1.js b/example/histogram-1.js
index 0c2b878a..b94e099d 100644
--- a/example/histogram-1.js
+++ b/example/histogram-1.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 // Histogram
diff --git a/example/histogram-2.js b/example/histogram-2.js
index de6be297..6eeddbef 100644
--- a/example/histogram-2.js
+++ b/example/histogram-2.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 // Histogram
diff --git a/example/histogram-3.js b/example/histogram-3.js
index e68858ff..9209d291 100644
--- a/example/histogram-3.js
+++ b/example/histogram-3.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 // Histogram
diff --git a/example/histogram-4.js b/example/histogram-4.js
index 4b6481cb..f2ce75b6 100644
--- a/example/histogram-4.js
+++ b/example/histogram-4.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 // Histogram
diff --git a/example/histogram-large-memory.js b/example/histogram-large-memory.js
index 5ff2976c..4d5e0ebc 100644
--- a/example/histogram-large-memory.js
+++ b/example/histogram-large-memory.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const v8 = require('v8');
diff --git a/example/pushgateway.js b/example/pushgateway.js
index 6341f9de..79648f66 100644
--- a/example/pushgateway.js
+++ b/example/pushgateway.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const client = require('../index');
diff --git a/example/server.js b/example/server.js
index a89afe0b..7290008c 100644
--- a/example/server.js
+++ b/example/server.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const express = require('express');
diff --git a/example/summary.js b/example/summary.js
index 08efcc46..b1af9f99 100644
--- a/example/summary.js
+++ b/example/summary.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 // Summary
diff --git a/example/worker.js b/example/worker.js
index 5a4553f0..2af9ea83 100644
--- a/example/worker.js
+++ b/example/worker.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Path = require('path');
diff --git a/index.d.ts b/index.d.ts
index 41a55f2c..8c0ebb2c 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 // Type definitions for @prometheus/client
 // Definitions by: Simon Nyberg http://twitter.com/siimon_nyberg
 
diff --git a/index.js b/index.js
index dfef5adc..52ca3631 100644
--- a/index.js
+++ b/index.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 /**
  * Prometheus client
  * @module Prometheus client
diff --git a/lib/bucketGenerators.js b/lib/bucketGenerators.js
index a9a487c7..d0b1a5cd 100644
--- a/lib/bucketGenerators.js
+++ b/lib/bucketGenerators.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 exports.linearBuckets = (start, width, count) => {
diff --git a/lib/cluster.js b/lib/cluster.js
index f17c0d6e..697482a3 100644
--- a/lib/cluster.js
+++ b/lib/cluster.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 /**
diff --git a/lib/counter.js b/lib/counter.js
index 5a84c226..7835c8de 100644
--- a/lib/counter.js
+++ b/lib/counter.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 /**
  * Counter metric
  */
diff --git a/lib/defaultMetrics.js b/lib/defaultMetrics.js
index 7d9a148d..9b6da6ee 100644
--- a/lib/defaultMetrics.js
+++ b/lib/defaultMetrics.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { isObject } = require('./util');
diff --git a/lib/exemplar.js b/lib/exemplar.js
index cb5d6780..137ab610 100644
--- a/lib/exemplar.js
+++ b/lib/exemplar.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 /**
diff --git a/lib/gauge.js b/lib/gauge.js
index a0d17b8f..789f620e 100644
--- a/lib/gauge.js
+++ b/lib/gauge.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 /**
  * Gauge metric
  */
diff --git a/lib/histogram.js b/lib/histogram.js
index 6655ad54..c87852c3 100644
--- a/lib/histogram.js
+++ b/lib/histogram.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 /**
  * Histogram
  */
diff --git a/lib/metric.js b/lib/metric.js
index e33933ad..0c519de0 100644
--- a/lib/metric.js
+++ b/lib/metric.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('./registry');
diff --git a/lib/metricAggregators.js b/lib/metricAggregators.js
index 8ea05281..6f897c16 100644
--- a/lib/metricAggregators.js
+++ b/lib/metricAggregators.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { LabelGrouper } = require('./util');
diff --git a/lib/metrics/eventLoopLag.js b/lib/metrics/eventLoopLag.js
index 644f92a3..af5090f8 100644
--- a/lib/metrics/eventLoopLag.js
+++ b/lib/metrics/eventLoopLag.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Gauge = require('../gauge');
diff --git a/lib/metrics/gc.js b/lib/metrics/gc.js
index 6e1c10b7..3d9b60d7 100644
--- a/lib/metrics/gc.js
+++ b/lib/metrics/gc.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 const Histogram = require('../histogram');
 
diff --git a/lib/metrics/heapSizeAndUsed.js b/lib/metrics/heapSizeAndUsed.js
index ae8a145d..a6e337f2 100644
--- a/lib/metrics/heapSizeAndUsed.js
+++ b/lib/metrics/heapSizeAndUsed.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Gauge = require('../gauge');
diff --git a/lib/metrics/heapSpacesSizeAndUsed.js b/lib/metrics/heapSpacesSizeAndUsed.js
index 9519a3b2..8c0639d3 100644
--- a/lib/metrics/heapSpacesSizeAndUsed.js
+++ b/lib/metrics/heapSpacesSizeAndUsed.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Gauge = require('../gauge');
diff --git a/lib/metrics/helpers/processMetricsHelpers.js b/lib/metrics/helpers/processMetricsHelpers.js
index d1f07630..b9214e9d 100644
--- a/lib/metrics/helpers/processMetricsHelpers.js
+++ b/lib/metrics/helpers/processMetricsHelpers.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 function aggregateByObjectName(list) {
diff --git a/lib/metrics/helpers/safeMemoryUsage.js b/lib/metrics/helpers/safeMemoryUsage.js
index 30fad883..eb586515 100644
--- a/lib/metrics/helpers/safeMemoryUsage.js
+++ b/lib/metrics/helpers/safeMemoryUsage.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 // process.memoryUsage() can throw on some platforms, see #67
diff --git a/lib/metrics/helpers/safeRss.js b/lib/metrics/helpers/safeRss.js
index 6b1ac2c5..dcd35ebd 100644
--- a/lib/metrics/helpers/safeRss.js
+++ b/lib/metrics/helpers/safeRss.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 // process.memoryUsage.rss() can throw on some platforms, see #67
diff --git a/lib/metrics/osMemoryHeap.js b/lib/metrics/osMemoryHeap.js
index 24ace2a9..1d05695b 100644
--- a/lib/metrics/osMemoryHeap.js
+++ b/lib/metrics/osMemoryHeap.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Gauge = require('../gauge');
diff --git a/lib/metrics/osMemoryHeapLinux.js b/lib/metrics/osMemoryHeapLinux.js
index 955c4cf3..4bdabc45 100644
--- a/lib/metrics/osMemoryHeapLinux.js
+++ b/lib/metrics/osMemoryHeapLinux.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Gauge = require('../gauge');
diff --git a/lib/metrics/processCpuTotal.js b/lib/metrics/processCpuTotal.js
index d0213094..a4671828 100644
--- a/lib/metrics/processCpuTotal.js
+++ b/lib/metrics/processCpuTotal.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const OtelApi = require('@opentelemetry/api');
diff --git a/lib/metrics/processHandles.js b/lib/metrics/processHandles.js
index 9a78d9f8..2996e5e0 100644
--- a/lib/metrics/processHandles.js
+++ b/lib/metrics/processHandles.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { aggregateByObjectName } = require('./helpers/processMetricsHelpers');
diff --git a/lib/metrics/processMaxFileDescriptors.js b/lib/metrics/processMaxFileDescriptors.js
index f71a85a7..81cfe777 100644
--- a/lib/metrics/processMaxFileDescriptors.js
+++ b/lib/metrics/processMaxFileDescriptors.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Gauge = require('../gauge');
diff --git a/lib/metrics/processOpenFileDescriptors.js b/lib/metrics/processOpenFileDescriptors.js
index 547a8e3a..6569c7d9 100644
--- a/lib/metrics/processOpenFileDescriptors.js
+++ b/lib/metrics/processOpenFileDescriptors.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Gauge = require('../gauge');
diff --git a/lib/metrics/processRequests.js b/lib/metrics/processRequests.js
index 2351f71d..3e2a41cf 100644
--- a/lib/metrics/processRequests.js
+++ b/lib/metrics/processRequests.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 const Gauge = require('../gauge');
 const { aggregateByObjectName } = require('./helpers/processMetricsHelpers');
diff --git a/lib/metrics/processResources.js b/lib/metrics/processResources.js
index 5e50d98b..7975cfbd 100644
--- a/lib/metrics/processResources.js
+++ b/lib/metrics/processResources.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 const Gauge = require('../gauge');
 const { updateMetrics } = require('./helpers/processMetricsHelpers');
diff --git a/lib/metrics/processStartTime.js b/lib/metrics/processStartTime.js
index d20018d3..35dd08ee 100644
--- a/lib/metrics/processStartTime.js
+++ b/lib/metrics/processStartTime.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Gauge = require('../gauge');
diff --git a/lib/metrics/version.js b/lib/metrics/version.js
index 7eabf9a5..98f5bf9b 100644
--- a/lib/metrics/version.js
+++ b/lib/metrics/version.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Gauge = require('../gauge');
diff --git a/lib/pushgateway.js b/lib/pushgateway.js
index 9b1261be..f43487b4 100644
--- a/lib/pushgateway.js
+++ b/lib/pushgateway.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const http = require('http');
diff --git a/lib/registry.js b/lib/registry.js
index 4d0906b1..9c9aeaf7 100644
--- a/lib/registry.js
+++ b/lib/registry.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { getValueAsString, Grouper } = require('./util');
diff --git a/lib/summary.js b/lib/summary.js
index 556e047c..94a14748 100644
--- a/lib/summary.js
+++ b/lib/summary.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 /**
  * Summary
  */
diff --git a/lib/timeWindowQuantiles.js b/lib/timeWindowQuantiles.js
index 176cb5b8..357e7dfd 100644
--- a/lib/timeWindowQuantiles.js
+++ b/lib/timeWindowQuantiles.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { TDigest } = require('tdigest');
diff --git a/lib/util.js b/lib/util.js
index 8b0ded20..18dca108 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const util = require('util');
diff --git a/lib/validation.js b/lib/validation.js
index 2472c000..ade09c69 100644
--- a/lib/validation.js
+++ b/lib/validation.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const util = require('util');
diff --git a/lib/worker.js b/lib/worker.js
index 8eb83971..48c1409f 100644
--- a/lib/worker.js
+++ b/lib/worker.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 /**
diff --git a/test/aggregatorsTest.js b/test/aggregatorsTest.js
index 0010a656..35ea65db 100644
--- a/test/aggregatorsTest.js
+++ b/test/aggregatorsTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 describe('aggregators', () => {
diff --git a/test/browserCompatibilityTest.js b/test/browserCompatibilityTest.js
index c6e2a779..7e8d0940 100644
--- a/test/browserCompatibilityTest.js
+++ b/test/browserCompatibilityTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 describe('Browser compatibility', () => {
diff --git a/test/bucketGeneratorsTest.js b/test/bucketGeneratorsTest.js
index c54d68ed..add1de57 100644
--- a/test/bucketGeneratorsTest.js
+++ b/test/bucketGeneratorsTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 describe('bucketGenerators', () => {
diff --git a/test/clusterTest.js b/test/clusterTest.js
index e6b89def..bd2141bc 100644
--- a/test/clusterTest.js
+++ b/test/clusterTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const cluster = require('cluster');
diff --git a/test/counterTest.js b/test/counterTest.js
index 0ee0fc2d..7fcf5a35 100644
--- a/test/counterTest.js
+++ b/test/counterTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../index').Registry;
diff --git a/test/defaultMetricsTest.js b/test/defaultMetricsTest.js
index 2021d799..ff41e70f 100644
--- a/test/defaultMetricsTest.js
+++ b/test/defaultMetricsTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../index').Registry;
diff --git a/test/exemplarsTest.js b/test/exemplarsTest.js
index f573d810..0ad65883 100644
--- a/test/exemplarsTest.js
+++ b/test/exemplarsTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../index').Registry;
diff --git a/test/gaugeTest.js b/test/gaugeTest.js
index c90df1ae..1eb1b5e0 100644
--- a/test/gaugeTest.js
+++ b/test/gaugeTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { Metric } = require('../lib/metric');
diff --git a/test/histogramTest.js b/test/histogramTest.js
index 5ec89f97..6d44253b 100644
--- a/test/histogramTest.js
+++ b/test/histogramTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../index').Registry;
diff --git a/test/metrics/eventLoopLagTest.js b/test/metrics/eventLoopLagTest.js
index 7c347bb0..8b992ee2 100644
--- a/test/metrics/eventLoopLagTest.js
+++ b/test/metrics/eventLoopLagTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../../index').Registry;
diff --git a/test/metrics/gcTest.js b/test/metrics/gcTest.js
index d5ecb469..e7fa89cf 100644
--- a/test/metrics/gcTest.js
+++ b/test/metrics/gcTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../../index').Registry;
diff --git a/test/metrics/heapSizeAndUsedTest.js b/test/metrics/heapSizeAndUsedTest.js
index 3c917ed6..73e2e6f8 100644
--- a/test/metrics/heapSizeAndUsedTest.js
+++ b/test/metrics/heapSizeAndUsedTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../../index').Registry;
diff --git a/test/metrics/heapSpacesSizeAndUsedTest.js b/test/metrics/heapSpacesSizeAndUsedTest.js
index c4c06ce7..73553370 100644
--- a/test/metrics/heapSpacesSizeAndUsedTest.js
+++ b/test/metrics/heapSpacesSizeAndUsedTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../../index').Registry;
diff --git a/test/metrics/maxFileDescriptorsTest.js b/test/metrics/maxFileDescriptorsTest.js
index 3921b871..221003fd 100644
--- a/test/metrics/maxFileDescriptorsTest.js
+++ b/test/metrics/maxFileDescriptorsTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const exec = require('child_process').execSync;
diff --git a/test/metrics/processHandlesTest.js b/test/metrics/processHandlesTest.js
index dd03404c..69f764c4 100644
--- a/test/metrics/processHandlesTest.js
+++ b/test/metrics/processHandlesTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../../index').Registry;
diff --git a/test/metrics/processOpenFileDescriptorsTest.js b/test/metrics/processOpenFileDescriptorsTest.js
index 7cc6c50b..36fca8f8 100644
--- a/test/metrics/processOpenFileDescriptorsTest.js
+++ b/test/metrics/processOpenFileDescriptorsTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../../index').Registry;
diff --git a/test/metrics/processRequestsTest.js b/test/metrics/processRequestsTest.js
index c28a51d2..eecdb81d 100644
--- a/test/metrics/processRequestsTest.js
+++ b/test/metrics/processRequestsTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../../index').Registry;
diff --git a/test/metrics/processResourcesTest.js b/test/metrics/processResourcesTest.js
index dd13dedc..7917649b 100644
--- a/test/metrics/processResourcesTest.js
+++ b/test/metrics/processResourcesTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 describe('processRequests', () => {
diff --git a/test/metrics/processStartTimeTest.js b/test/metrics/processStartTimeTest.js
index bee5cdab..4468db79 100644
--- a/test/metrics/processStartTimeTest.js
+++ b/test/metrics/processStartTimeTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../../index').Registry;
diff --git a/test/metrics/versionTest.js b/test/metrics/versionTest.js
index 0a28fb0e..0f2cbc4e 100644
--- a/test/metrics/versionTest.js
+++ b/test/metrics/versionTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../../index').Registry;
diff --git a/test/pushgatewayTest.js b/test/pushgatewayTest.js
index 812b1199..3001613d 100644
--- a/test/pushgatewayTest.js
+++ b/test/pushgatewayTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const nock = require('nock');
diff --git a/test/pushgatewayWithPathTest.js b/test/pushgatewayWithPathTest.js
index 7dd75427..081f79d1 100644
--- a/test/pushgatewayWithPathTest.js
+++ b/test/pushgatewayWithPathTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const pushGatewayPath = '/path';
diff --git a/test/registerTest.js b/test/registerTest.js
index ed2c8c24..ce4a8757 100644
--- a/test/registerTest.js
+++ b/test/registerTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../index').Registry;
diff --git a/test/summaryTest.js b/test/summaryTest.js
index 306c9b8b..30cfe1cb 100644
--- a/test/summaryTest.js
+++ b/test/summaryTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const Registry = require('../index').Registry;
diff --git a/test/timeWindowQuantilesTest.js b/test/timeWindowQuantilesTest.js
index cda7c181..8adc9bd1 100644
--- a/test/timeWindowQuantilesTest.js
+++ b/test/timeWindowQuantilesTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 describe('timeWindowQuantiles', () => {
diff --git a/test/typescript.ts b/test/typescript.ts
index 13840a38..80d899ce 100644
--- a/test/typescript.ts
+++ b/test/typescript.ts
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 import { Counter, Pushgateway, Registry } from '../index';
 
 const registry = new Registry();
diff --git a/test/utilTest.js b/test/utilTest.js
index 0eae56d9..c1fe8ebc 100644
--- a/test/utilTest.js
+++ b/test/utilTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 describe('utils', () => {
diff --git a/test/validationTest.js b/test/validationTest.js
index 27bb97f6..8b94a69b 100644
--- a/test/validationTest.js
+++ b/test/validationTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 describe('validation', () => {
diff --git a/test/workerTest.js b/test/workerTest.js
index eb043c0a..9f28d467 100644
--- a/test/workerTest.js
+++ b/test/workerTest.js
@@ -1,3 +1,17 @@
+// Copyright The Prometheus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 'use strict';
 
 const { EventEmitter } = require('events');