diff --git a/.github/ISSUE_TEMPLATE/bug_report.yml b/.github/ISSUE_TEMPLATE/bug_report.yml
index 03d520c..debb2ad 100644
--- a/.github/ISSUE_TEMPLATE/bug_report.yml
+++ b/.github/ISSUE_TEMPLATE/bug_report.yml
@@ -63,7 +63,7 @@ body:
     id: gpdf-version
     attributes:
       label: gpdf Version
-      placeholder: "v1.0.0"
+      placeholder: "v1.0.2"
     validations:
       required: true
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2f6b9e3..c0c518b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+## [1.0.2] - 2026-03-23
+
+### Added
+- PDF document merging — combine pages from multiple PDFs into one (#11)
+  - `pdf.MergePDFs()`: Core merge engine with object reference remapping
+  - `gpdf.Merge()`: High-level facade with `Source`, `PageRange`, `WithMergeMetadata()`
+  - `pdf.Writer.AddRawPage()`, `PageTreeRef()`: Raw page insertion support
+  - Merge examples: basic merge, page range extraction, metadata, merge + overlay, issue #11 scenario
+
+## [1.0.0] - 2026-03-20
+
 ### Added
 - Existing PDF overlay — open, read, and modify existing PDFs
   - `pdf.Reader`: PDF parser with XRef table/stream parsing, page tree traversal, object caching
@@ -91,8 +102,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/).
 - Reed-Solomon coefficient order in QR code encoder
 - binary.Write return value handling for errcheck lint
 
-[Unreleased]: https://github.com/gpdf-dev/gpdf/compare/v1.0.0...HEAD
-[0.9.0]: https://github.com/gpdf-dev/gpdf/compare/v0.8.0...v1.0.0
+[Unreleased]: https://github.com/gpdf-dev/gpdf/compare/v1.0.2...HEAD
+[1.0.2]: https://github.com/gpdf-dev/gpdf/compare/v1.0.0...v1.0.2
+[1.0.0]: https://github.com/gpdf-dev/gpdf/compare/v0.9.0...v1.0.0
+[0.9.0]: https://github.com/gpdf-dev/gpdf/compare/v0.8.0...v0.9.0
 [0.8.0]: https://github.com/gpdf-dev/gpdf/compare/v0.5.0...v0.8.0
 [0.7.0]: https://github.com/gpdf-dev/gpdf/releases/tag/v0.7.0
 [0.6.0]: https://github.com/gpdf-dev/gpdf/releases/tag/v0.6.0
diff --git a/README.md b/README.md
index 2329c59..e67916a 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 [![Go Reference](https://pkg.go.dev/badge/github.com/gpdf-dev/gpdf.svg)](https://pkg.go.dev/github.com/gpdf-dev/gpdf)
 [![CI](https://github.com/gpdf-dev/gpdf/actions/workflows/check-code.yml/badge.svg)](https://github.com/gpdf-dev/gpdf/actions/workflows/check-code.yml)
-![coverage](https://img.shields.io/badge/coverage-86.8%25-green)
+![coverage](https://img.shields.io/badge/coverage-86.5%25-green)
 [![Go Report Card](https://goreportcard.com/badge/github.com/gpdf-dev/gpdf)](https://goreportcard.com/report/github.com/gpdf-dev/gpdf)
 [![Go Version](https://img.shields.io/badge/Go-%3E%3D1.22-blue)](https://go.dev/)
 [![Website](https://img.shields.io/badge/Website-gpdf.dev-blue)](https://gpdf.dev/)
@@ -33,6 +33,7 @@ A pure Go, zero-dependency PDF generation library with a layered architecture an
 - **Images** — JPEG and PNG embedding with fit options
 - **Absolute positioning** — place elements at exact XY coordinates on the page
 - **Existing PDF overlay** — open existing PDFs and add text, images, stamps on top
+- **PDF merging** — combine multiple PDFs into one with page range selection
 - **Document metadata** — title, author, subject, creator
 - **Encryption** — AES-256 encryption (ISO 32000-2, Rev 6) with owner/user passwords and permissions
 - **PDF/A** — PDF/A-1b and PDF/A-2b conformance with ICC profiles and XMP metadata
@@ -498,6 +499,22 @@ doc.EachPage(func(i int, p *template.PageBuilder) {
 result, _ := doc.Save()
 ```
 
+### PDF Merging
+
+Combine multiple PDFs into a single document with optional page range selection:
+
+```go
+// Merge multiple PDFs
+merged, _ := gpdf.Merge(
+	[]gpdf.Source{
+		{Data: coverPage},
+		{Data: report},
+		{Data: appendix, Pages: gpdf.PageRange{From: 1, To: 3}}, // only first 3 pages
+	},
+	gpdf.WithMergeMetadata("My Document", "Author", ""),
+)
+```
+
 ### JSON Schema
 
 Define documents entirely in JSON:
@@ -780,6 +797,8 @@ doc.Render(f)
 | `doc.Overlay(page, fn)` | Add content on top of a specific page |
 | `doc.EachPage(fn)` | Apply overlay to every page |
 | `doc.Save()` | Save the modified PDF |
+| `gpdf.Merge(sources, opts...)` | Merge multiple PDFs into one |
+| `WithMergeMetadata(title, author, producer)` | Set metadata on merged output |
 
 ### Text Options
 
diff --git a/README_es.md b/README_es.md
index c2e3322..70708bd 100644
--- a/README_es.md
+++ b/README_es.md
@@ -32,6 +32,7 @@ Biblioteca de generación de PDF en Go puro, sin dependencias externas, con arqu
 - **Imágenes** — incrustación de JPEG y PNG con opciones de ajuste
 - **Posicionamiento absoluto** — colocar elementos en coordenadas XY exactas en la página
 - **Superposición de PDF existente** — abrir PDFs existentes y agregar texto, imágenes, sellos encima
+- **Fusión de PDF** — combinar múltiples PDFs en uno con selección de rango de páginas
 - **Metadatos del documento** — título, autor, asunto, creador
 - **Encriptación** — encriptación AES-256 (ISO 32000-2, Rev 6) con contraseñas de propietario/usuario y permisos
 - **PDF/A** — conformidad PDF/A-1b y PDF/A-2b con perfiles ICC y metadatos XMP
@@ -415,6 +416,22 @@ doc.EachPage(func(i int, p *template.PageBuilder) {
 result, _ := doc.Save()
 ```
 
+### Fusión de PDF
+
+Combine múltiples PDFs en un solo documento con selección opcional de rango de páginas:
+
+```go
+// Fusionar múltiples PDFs
+merged, _ := gpdf.Merge(
+	[]gpdf.Source{
+		{Data: coverPage},
+		{Data: report},
+		{Data: appendix, Pages: gpdf.PageRange{From: 1, To: 3}}, // solo las primeras 3 páginas
+	},
+	gpdf.WithMergeMetadata("My Document", "Author", ""),
+)
+```
+
 ### Metadatos del documento
 
 ```go
@@ -519,6 +536,8 @@ doc.Render(f)
 | `doc.Overlay(page, fn)` | Superponer contenido en una página específica |
 | `doc.EachPage(fn)` | Aplicar superposición a todas las páginas |
 | `doc.Save()` | Guardar el PDF modificado |
+| `gpdf.Merge(sources, opts...)` | Fusionar múltiples PDFs en uno |
+| `WithMergeMetadata(title, author, producer)` | Establecer metadatos en la salida fusionada |
 
 ### Opciones de texto
 
diff --git a/README_ja.md b/README_ja.md
index 48706d9..b30cca3 100644
--- a/README_ja.md
+++ b/README_ja.md
@@ -32,6 +32,7 @@
 - **画像** — JPEGとPNGの埋め込み（フィットオプション対応）
 - **絶対位置指定** — ページ上の任意のXY座標に要素を配置
 - **既存PDFオーバーレイ** — 既存PDFを開いてテキスト、画像、スタンプを上に追加
+- **PDFマージ** — 複数のPDFをページ範囲指定付きで1つに結合
 - **ドキュメントメタデータ** — タイトル、著者、件名、作成者
 - **暗号化** — AES-256暗号化（ISO 32000-2, Rev 6）、オーナー/ユーザーパスワードと権限制御
 - **PDF/A** — PDF/A-1bおよびPDF/A-2b準拠、ICCプロファイルとXMPメタデータ対応
@@ -424,6 +425,22 @@ doc.EachPage(func(i int, p *template.PageBuilder) {
 result, _ := doc.Save()
 ```
 
+### PDFマージ
+
+複数のPDFをページ範囲指定付きで1つのドキュメントに結合:
+
+```go
+// 複数のPDFを結合
+merged, _ := gpdf.Merge(
+	[]gpdf.Source{
+		{Data: coverPage},
+		{Data: report},
+		{Data: appendix, Pages: gpdf.PageRange{From: 1, To: 3}}, // 最初の3ページのみ
+	},
+	gpdf.WithMergeMetadata("My Document", "Author", ""),
+)
+```
+
 ### JSONスキーマ
 
 JSONのみでドキュメントを定義:
@@ -638,6 +655,8 @@ doc.Render(f)
 | `doc.Overlay(page, fn)` | 特定ページにコンテンツを重ねて配置 |
 | `doc.EachPage(fn)` | 全ページにオーバーレイを適用 |
 | `doc.Save()` | 変更したPDFを保存 |
+| `gpdf.Merge(sources, opts...)` | 複数のPDFを1つに結合 |
+| `WithMergeMetadata(title, author, producer)` | 結合後のメタデータを設定 |
 
 ### テキストオプション
 
diff --git a/README_ko.md b/README_ko.md
index bce68af..2f60d40 100644
--- a/README_ko.md
+++ b/README_ko.md
@@ -32,6 +32,7 @@
 - **이미지** — JPEG 및 PNG 임베딩 (맞춤 옵션 지원)
 - **절대 위치 지정** — 페이지의 정확한 XY 좌표에 요소 배치
 - **기존 PDF 오버레이** — 기존 PDF를 열어 텍스트, 이미지, 스탬프를 위에 추가
+- **PDF 병합** — 여러 PDF를 페이지 범위 선택으로 하나로 결합
 - **문서 메타데이터** — 제목, 저자, 주제, 작성자
 - **암호화** — AES-256 암호화 (ISO 32000-2, Rev 6), 소유자/사용자 비밀번호 및 권한 제어
 - **PDF/A** — PDF/A-1b 및 PDF/A-2b 준수, ICC 프로파일 및 XMP 메타데이터 포함
@@ -415,6 +416,22 @@ doc.EachPage(func(i int, p *template.PageBuilder) {
 result, _ := doc.Save()
 ```
 
+### PDF 병합
+
+여러 PDF를 페이지 범위 선택으로 하나의 문서로 결합:
+
+```go
+// 여러 PDF 합치기
+merged, _ := gpdf.Merge(
+	[]gpdf.Source{
+		{Data: coverPage},
+		{Data: report},
+		{Data: appendix, Pages: gpdf.PageRange{From: 1, To: 3}}, // 처음 3페이지만
+	},
+	gpdf.WithMergeMetadata("My Document", "Author", ""),
+)
+```
+
 ### 문서 메타데이터
 
 ```go
@@ -519,6 +536,8 @@ doc.Render(f)
 | `doc.Overlay(page, fn)` | 특정 페이지에 콘텐츠 오버레이 |
 | `doc.EachPage(fn)` | 모든 페이지에 오버레이 적용 |
 | `doc.Save()` | 수정된 PDF 저장 |
+| `gpdf.Merge(sources, opts...)` | 여러 PDF를 하나로 병합 |
+| `WithMergeMetadata(title, author, producer)` | 병합된 출력의 메타데이터 설정 |
 
 ### 텍스트 옵션
 
diff --git a/README_pt.md b/README_pt.md
index dddef76..ead2f0f 100644
--- a/README_pt.md
+++ b/README_pt.md
@@ -32,6 +32,7 @@ Biblioteca de geração de PDF em Go puro, sem dependências externas, com arqui
 - **Imagens** — incorporação de JPEG e PNG com opções de ajuste
 - **Posicionamento absoluto** — posicionar elementos em coordenadas XY exatas na página
 - **Sobreposição de PDF existente** — abrir PDFs existentes e adicionar texto, imagens, carimbos por cima
+- **Fusão de PDF** — combinar múltiplos PDFs em um com seleção de intervalo de páginas
 - **Metadados do documento** — título, autor, assunto, criador
 - **Criptografia** — criptografia AES-256 (ISO 32000-2, Rev 6) com senhas de proprietário/usuário e permissões
 - **PDF/A** — conformidade PDF/A-1b e PDF/A-2b com perfis ICC e metadados XMP
@@ -466,6 +467,22 @@ doc.EachPage(func(i int, p *template.PageBuilder) {
 result, _ := doc.Save()
 ```
 
+### Fusão de PDF
+
+Combine múltiplos PDFs em um único documento com seleção opcional de intervalo de páginas:
+
+```go
+// Fundir múltiplos PDFs
+merged, _ := gpdf.Merge(
+	[]gpdf.Source{
+		{Data: coverPage},
+		{Data: report},
+		{Data: appendix, Pages: gpdf.PageRange{From: 1, To: 3}}, // apenas as primeiras 3 páginas
+	},
+	gpdf.WithMergeMetadata("My Document", "Author", ""),
+)
+```
+
 ## Referência API
 
 ### Opções do documento
@@ -519,6 +536,8 @@ result, _ := doc.Save()
 | `doc.Overlay(page, fn)` | Sobrepor conteúdo em uma página específica |
 | `doc.EachPage(fn)` | Aplicar sobreposição em todas as páginas |
 | `doc.Save()` | Salvar o PDF modificado |
+| `gpdf.Merge(sources, opts...)` | Fundir múltiplos PDFs em um |
+| `WithMergeMetadata(title, author, producer)` | Definir metadados na saída fundida |
 
 ### Opções de texto
 
diff --git a/README_zh.md b/README_zh.md
index 69dfa67..cc2f9fd 100644
--- a/README_zh.md
+++ b/README_zh.md
@@ -32,6 +32,7 @@
 - **图片** — JPEG 和 PNG 嵌入（支持缩放选项）
 - **绝对定位** — 在页面上以精确 XY 坐标放置元素
 - **现有 PDF 叠加** — 打开现有 PDF 并在上面添加文字、图片、印章
+- **PDF 合并** — 将多个 PDF 合并为一个，支持页面范围选择
 - **文档元数据** — 标题、作者、主题、创建者
 - **加密** — AES-256 加密（ISO 32000-2, Rev 6），支持所有者/用户密码和权限控制
 - **PDF/A** — PDF/A-1b 和 PDF/A-2b 合规，包含 ICC 配置文件和 XMP 元数据
@@ -415,6 +416,22 @@ doc.EachPage(func(i int, p *template.PageBuilder) {
 result, _ := doc.Save()
 ```
 
+### PDF 合并
+
+将多个 PDF 合并为一个文档，支持页面范围选择：
+
+```go
+// 合并多个 PDF
+merged, _ := gpdf.Merge(
+	[]gpdf.Source{
+		{Data: coverPage},
+		{Data: report},
+		{Data: appendix, Pages: gpdf.PageRange{From: 1, To: 3}}, // 仅前 3 页
+	},
+	gpdf.WithMergeMetadata("My Document", "Author", ""),
+)
+```
+
 ### 文档元数据
 
 ```go
@@ -519,6 +536,8 @@ doc.Render(f)
 | `doc.Overlay(page, fn)` | 在指定页上叠加内容 |
 | `doc.EachPage(fn)` | 对每页应用叠加 |
 | `doc.Save()` | 保存修改后的 PDF |
+| `gpdf.Merge(sources, opts...)` | 将多个 PDF 合并为一个 |
+| `WithMergeMetadata(title, author, producer)` | 设置合并后的元数据 |
 
 ### 文本选项
 
diff --git a/_benchmark/go.mod b/_benchmark/go.mod
index f800c8c..d0e979b 100644
--- a/_benchmark/go.mod
+++ b/_benchmark/go.mod
@@ -5,24 +5,24 @@ go 1.24
 replace github.com/gpdf-dev/gpdf => ../
 
 require (
-	github.com/go-pdf/fpdf v1.0.0
+	github.com/go-pdf/fpdf v1.0.2
 	github.com/johnfercher/maroto/v2 v2.3.3
-	github.com/gpdf-dev/gpdf v1.0.1
+	github.com/gpdf-dev/gpdf v1.0.2
 	github.com/signintech/gopdf v0.36.0
 	golang.org/x/image v0.18.0
 )
 
 require (
-	github.com/boombuler/barcode v1.0.1 // indirect
+	github.com/boombuler/barcode v1.0.2 // indirect
 	github.com/f-amaral/go-async v0.3.0 // indirect
 	github.com/google/uuid v1.5.0 // indirect
-	github.com/hhrutter/lzw v1.0.0 // indirect
-	github.com/hhrutter/tiff v1.0.1 // indirect
+	github.com/hhrutter/lzw v1.0.2 // indirect
+	github.com/hhrutter/tiff v1.0.2 // indirect
 	github.com/johnfercher/go-tree v1.0.5 // indirect
 	github.com/mattn/go-runewidth v0.0.15 // indirect
 	github.com/pdfcpu/pdfcpu v0.6.0 // indirect
 	github.com/phpdave11/gofpdf v1.4.3 // indirect
-	github.com/phpdave11/gofpdi v1.0.15 // indirect
+	github.com/phpdave11/gofpdi v1.0.25 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/rivo/uniseg v0.4.4 // indirect
 	golang.org/x/text v0.22.0 // indirect
diff --git a/_benchmark/go.sum b/_benchmark/go.sum
index 62c9eed..c24384d 100644
--- a/_benchmark/go.sum
+++ b/_benchmark/go.sum
@@ -1,38 +1,38 @@
-github.com/boombuler/barcode v1.0.0/go.mod h1:paBWMcWSl3LHKBqUq+rly7CNSldXjb2rDl3JlRe0mD8=
-github.com/boombuler/barcode v1.0.1 h1:NDBbPmhS+EqABEs5Kg3n/5ZNjy73Pz7SIV+KCeqyXcs=
-github.com/boombuler/barcode v1.0.1/go.mod h1:paBWMcWSl3LHKBqUq+rly7CNSldXjb2rDl3JlRe0mD8=
+github.com/boombuler/barcode v1.0.2/go.mod h1:paBWMcWSl3LHKBqUq+rly7CNSldXjb2rDl3JlRe0mD8=
+github.com/boombuler/barcode v1.0.2 h1:NDBbPmhS+EqABEs5Kg3n/5ZNjy73Pz7SIV+KCeqyXcs=
+github.com/boombuler/barcode v1.0.2/go.mod h1:paBWMcWSl3LHKBqUq+rly7CNSldXjb2rDl3JlRe0mD8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/f-amaral/go-async v0.3.0 h1:h4kLsX7aKfdWaHvV0lf+/EE3OIeCzyeDYJDb/vDZUyg=
 github.com/f-amaral/go-async v0.3.0/go.mod h1:Hz5Qr6DAWpbTTUjytnrg1WIsDgS7NtOei5y8SipYS7U=
-github.com/go-pdf/fpdf v1.0.0 h1:PPvSaUuo1iMi9KkaAn90NuKi+P4gwMedWPHhj8YlJQw=
-github.com/go-pdf/fpdf v1.0.0/go.mod h1:oO8N111TkmKb9D7VvWGLvLJlaZUQVPM+6V42pp3iV4Y=
+github.com/go-pdf/fpdf v1.0.2 h1:PPvSaUuo1iMi9KkaAn90NuKi+P4gwMedWPHhj8YlJQw=
+github.com/go-pdf/fpdf v1.0.2/go.mod h1:oO8N111TkmKb9D7VvWGLvLJlaZUQVPM+6V42pp3iV4Y=
 github.com/google/uuid v1.5.0 h1:1p67kYwdtXjb0gL0BPiP1Av9wiZPo5A8z2cWkTZ+eyU=
 github.com/google/uuid v1.5.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
-github.com/hhrutter/lzw v1.0.0 h1:laL89Llp86W3rRs83LvKbwYRx6INE8gDn0XNb1oXtm0=
-github.com/hhrutter/lzw v1.0.0/go.mod h1:2HC6DJSn/n6iAZfgM3Pg+cP1KxeWc3ezG8bBqW5+WEo=
-github.com/hhrutter/tiff v1.0.1 h1:MIus8caHU5U6823gx7C6jrfoEvfSTGtEFRiM8/LOzC0=
-github.com/hhrutter/tiff v1.0.1/go.mod h1:zU/dNgDm0cMIa8y8YwcYBeuEEveI4B0owqHyiPpJPHc=
+github.com/hhrutter/lzw v1.0.2 h1:laL89Llp86W3rRs83LvKbwYRx6INE8gDn0XNb1oXtm0=
+github.com/hhrutter/lzw v1.0.2/go.mod h1:2HC6DJSn/n6iAZfgM3Pg+cP1KxeWc3ezG8bBqW5+WEo=
+github.com/hhrutter/tiff v1.0.2 h1:MIus8caHU5U6823gx7C6jrfoEvfSTGtEFRiM8/LOzC0=
+github.com/hhrutter/tiff v1.0.2/go.mod h1:zU/dNgDm0cMIa8y8YwcYBeuEEveI4B0owqHyiPpJPHc=
 github.com/johnfercher/go-tree v1.0.5 h1:zpgVhJsChavzhKdxhQiCJJzcSY3VCT9oal2JoA2ZevY=
 github.com/johnfercher/go-tree v1.0.5/go.mod h1:DUO6QkXIFh1K7jeGBIkLCZaeUgnkdQAsB64FDSoHswg=
 github.com/johnfercher/maroto/v2 v2.3.3 h1:oeXsBnoecaMgRDwN0Cstjoe4rug3lKpOanuxuHKPqQE=
 github.com/johnfercher/maroto/v2 v2.3.3/go.mod h1:KNv102TwUrlVgZGukzlIbhkG6l/WaCD6pzu6aWGVjBI=
-github.com/jung-kurt/gofpdf v1.0.0/go.mod h1:7Id9E/uU8ce6rXgefFLlgrJj/GYY22cpxn+r32jIOes=
+github.com/jung-kurt/gofpdf v1.0.2/go.mod h1:7Id9E/uU8ce6rXgefFLlgrJj/GYY22cpxn+r32jIOes=
 github.com/mattn/go-runewidth v0.0.15 h1:UNAjwbU9l54TA3KzvqLGxwWjHmMgBUVhBiTjelZgg3U=
 github.com/mattn/go-runewidth v0.0.15/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
 github.com/pdfcpu/pdfcpu v0.6.0 h1:z4kARP5bcWa39TTYMcN/kjBnm7MvhTWjXgeYmkdAGMI=
 github.com/pdfcpu/pdfcpu v0.6.0/go.mod h1:kmpD0rk8YnZj0l3qSeGBlAB+XszHUgNv//ORH/E7EYo=
 github.com/phpdave11/gofpdf v1.4.3 h1:M/zHvS8FO3zh9tUd2RCOPEjyuVcs281FCyF22Qlz/IA=
 github.com/phpdave11/gofpdf v1.4.3/go.mod h1:MAwzoUIgD3J55u0rxIG2eu37c+XWhBtXSpPAhnQXf/o=
-github.com/phpdave11/gofpdi v1.0.14-0.20211212211723-1f10f9844311/go.mod h1:vBmVV0Do6hSBHC8uKUQ71JGW+ZGQq74llk/7bXwjDoI=
-github.com/phpdave11/gofpdi v1.0.15 h1:iJazY1BQ07I9s7N5EWjBO1YbhmKfHGxNligUv/Rw4Lc=
-github.com/phpdave11/gofpdi v1.0.15/go.mod h1:vBmVV0Do6hSBHC8uKUQ71JGW+ZGQq74llk/7bXwjDoI=
+github.com/phpdave11/gofpdi v1.0.24-0.20211212211723-1f10f9844311/go.mod h1:vBmVV0Do6hSBHC8uKUQ71JGW+ZGQq74llk/7bXwjDoI=
+github.com/phpdave11/gofpdi v1.0.25 h1:iJazY1BQ07I9s7N5EWjBO1YbhmKfHGxNligUv/Rw4Lc=
+github.com/phpdave11/gofpdi v1.0.25/go.mod h1:vBmVV0Do6hSBHC8uKUQ71JGW+ZGQq74llk/7bXwjDoI=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
-github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/pmezard/go-difflib v1.0.2 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
 github.com/rivo/uniseg v0.4.4 h1:8TfxU8dW6PdqD27gjM8MVNuicgxIjxpm4K7x4jp8sis=
 github.com/rivo/uniseg v0.4.4/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
diff --git a/_examples/merge/01_basic_merge_test.go b/_examples/merge/01_basic_merge_test.go
new file mode 100644
index 0000000..c419c28
--- /dev/null
+++ b/_examples/merge/01_basic_merge_test.go
@@ -0,0 +1,74 @@
+package merge_test
+
+import (
+	"fmt"
+	"testing"
+
+	gpdf "github.com/gpdf-dev/gpdf"
+	"github.com/gpdf-dev/gpdf/_examples/testutil"
+	"github.com/gpdf-dev/gpdf/document"
+	"github.com/gpdf-dev/gpdf/template"
+)
+
+// generateDoc creates a PDF with the given number of pages and a title prefix.
+func generateDoc(t *testing.T, numPages int, prefix string) []byte {
+	t.Helper()
+	doc := template.New(
+		template.WithPageSize(document.A4),
+		template.WithMargins(document.UniformEdges(document.Mm(20))),
+		template.WithMetadata(document.DocumentMetadata{
+			Title:  prefix,
+			Author: "gpdf",
+		}),
+	)
+
+	for i := 1; i <= numPages; i++ {
+		page := doc.AddPage()
+		page.AutoRow(func(r *template.RowBuilder) {
+			r.Col(12, func(c *template.ColBuilder) {
+				c.Text(fmt.Sprintf("%s — Page %d", prefix, i),
+					template.FontSize(18), template.Bold())
+			})
+		})
+		page.AutoRow(func(r *template.RowBuilder) {
+			r.Col(12, func(c *template.ColBuilder) {
+				c.Spacer(document.Mm(5))
+				c.Line()
+				c.Spacer(document.Mm(5))
+			})
+		})
+		for j := 0; j < 3; j++ {
+			page.AutoRow(func(r *template.RowBuilder) {
+				r.Col(12, func(c *template.ColBuilder) {
+					c.Text("Lorem ipsum dolor sit amet, consectetur adipiscing elit. " +
+						"Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.",
+					)
+				})
+			})
+		}
+	}
+
+	data, err := doc.Generate()
+	if err != nil {
+		t.Fatalf("generate %s: %v", prefix, err)
+	}
+	return data
+}
+
+func TestExample_Merge_01_Basic(t *testing.T) {
+	// Generate two separate PDFs.
+	cover := generateDoc(t, 1, "Cover Page")
+	body := generateDoc(t, 3, "Report Body")
+
+	// Merge them into a single document.
+	merged, err := gpdf.Merge([]gpdf.Source{
+		{Data: cover},
+		{Data: body},
+	})
+	if err != nil {
+		t.Fatalf("Merge: %v", err)
+	}
+
+	testutil.AssertValidPDF(t, merged)
+	testutil.WritePDF(t, "01_basic_merge.pdf", merged)
+}
diff --git a/_examples/merge/02_page_range_test.go b/_examples/merge/02_page_range_test.go
new file mode 100644
index 0000000..c0368cc
--- /dev/null
+++ b/_examples/merge/02_page_range_test.go
@@ -0,0 +1,24 @@
+package merge_test
+
+import (
+	"testing"
+
+	gpdf "github.com/gpdf-dev/gpdf"
+	"github.com/gpdf-dev/gpdf/_examples/testutil"
+)
+
+func TestExample_Merge_02_PageRange(t *testing.T) {
+	// Generate a 5-page document.
+	full := generateDoc(t, 5, "Full Document")
+
+	// Extract only pages 2-4 (1-based).
+	extracted, err := gpdf.Merge([]gpdf.Source{
+		{Data: full, Pages: gpdf.PageRange{From: 2, To: 4}},
+	})
+	if err != nil {
+		t.Fatalf("Merge: %v", err)
+	}
+
+	testutil.AssertValidPDF(t, extracted)
+	testutil.WritePDF(t, "02_page_range.pdf", extracted)
+}
diff --git a/_examples/merge/03_metadata_test.go b/_examples/merge/03_metadata_test.go
new file mode 100644
index 0000000..cde544a
--- /dev/null
+++ b/_examples/merge/03_metadata_test.go
@@ -0,0 +1,30 @@
+package merge_test
+
+import (
+	"testing"
+
+	gpdf "github.com/gpdf-dev/gpdf"
+	"github.com/gpdf-dev/gpdf/_examples/testutil"
+)
+
+func TestExample_Merge_03_Metadata(t *testing.T) {
+	cover := generateDoc(t, 1, "Cover")
+	body := generateDoc(t, 2, "Body")
+	appendix := generateDoc(t, 1, "Appendix")
+
+	// Merge with custom metadata.
+	merged, err := gpdf.Merge(
+		[]gpdf.Source{
+			{Data: cover},
+			{Data: body},
+			{Data: appendix},
+		},
+		gpdf.WithMergeMetadata("Policy Bundle", "Example Ltd", "gpdf"),
+	)
+	if err != nil {
+		t.Fatalf("Merge: %v", err)
+	}
+
+	testutil.AssertValidPDF(t, merged)
+	testutil.WritePDF(t, "03_metadata.pdf", merged)
+}
diff --git a/_examples/merge/04_merge_and_overlay_test.go b/_examples/merge/04_merge_and_overlay_test.go
new file mode 100644
index 0000000..9247e75
--- /dev/null
+++ b/_examples/merge/04_merge_and_overlay_test.go
@@ -0,0 +1,56 @@
+package merge_test
+
+import (
+	"fmt"
+	"testing"
+
+	gpdf "github.com/gpdf-dev/gpdf"
+	"github.com/gpdf-dev/gpdf/_examples/testutil"
+	"github.com/gpdf-dev/gpdf/document"
+	"github.com/gpdf-dev/gpdf/pdf"
+	"github.com/gpdf-dev/gpdf/template"
+)
+
+func TestExample_Merge_04_MergeAndOverlay(t *testing.T) {
+	// Generate two PDFs and merge them.
+	part1 := generateDoc(t, 2, "Part 1")
+	part2 := generateDoc(t, 2, "Part 2")
+
+	merged, err := gpdf.Merge([]gpdf.Source{
+		{Data: part1},
+		{Data: part2},
+	})
+	if err != nil {
+		t.Fatalf("Merge: %v", err)
+	}
+
+	// Open the merged PDF and add page numbers on every page.
+	doc, err := gpdf.Open(merged)
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+
+	pageCount, err := doc.PageCount()
+	if err != nil {
+		t.Fatalf("PageCount: %v", err)
+	}
+	err = doc.EachPage(func(pageIndex int, p *template.PageBuilder) {
+		p.Absolute(document.Mm(95), document.Mm(285), func(c *template.ColBuilder) {
+			c.Text(fmt.Sprintf("Page %d / %d", pageIndex+1, pageCount),
+				template.FontSize(9),
+				template.TextColor(pdf.Gray(0.4)),
+			)
+		})
+	})
+	if err != nil {
+		t.Fatalf("EachPage: %v", err)
+	}
+
+	result, err := doc.Save()
+	if err != nil {
+		t.Fatalf("Save: %v", err)
+	}
+
+	testutil.AssertValidPDF(t, result)
+	testutil.WritePDF(t, "04_merge_and_overlay.pdf", result)
+}
diff --git a/_examples/merge/05_issue11_example_test.go b/_examples/merge/05_issue11_example_test.go
new file mode 100644
index 0000000..9f24143
--- /dev/null
+++ b/_examples/merge/05_issue11_example_test.go
@@ -0,0 +1,60 @@
+package merge_test
+
+import (
+	"testing"
+
+	gpdf "github.com/gpdf-dev/gpdf"
+	"github.com/gpdf-dev/gpdf/_examples/testutil"
+	"github.com/gpdf-dev/gpdf/document"
+	"github.com/gpdf-dev/gpdf/template"
+)
+
+func TestExample_Merge_05_Issue11(t *testing.T) {
+	// 1. Read existing PDFs (simulated with generated docs)
+	coverPage := generateDoc(t, 1, "Cover Page")
+	attachment := generateDoc(t, 5, "Terms and Conditions")
+
+	// 2. Generate a document with gpdf as normal
+	doc := template.New(
+		template.WithPageSize(document.A4),
+		template.WithMargins(document.Edges{
+			Top:    document.Pt(40),
+			Left:   document.Pt(40),
+			Right:  document.Pt(40),
+			Bottom: document.Pt(60),
+		}),
+	)
+	page := doc.AddPage()
+	page.AutoRow(func(r *template.RowBuilder) {
+		r.Col(12, func(c *template.ColBuilder) {
+			c.Text("Policy Certificate", template.FontSize(18), template.Bold())
+		})
+	})
+	page.AutoRow(func(r *template.RowBuilder) {
+		r.Col(12, func(c *template.ColBuilder) {
+			c.Text("Lorem ipsum dolor sit amet, consectetur adipiscing elit. " +
+				"Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.",
+			)
+		})
+	})
+	generated, err := doc.Generate()
+	if err != nil {
+		t.Fatalf("Generate: %v", err)
+	}
+
+	// 3. Merge: cover + generated + attachment
+	merged, err := gpdf.Merge(
+		[]gpdf.Source{
+			{Data: coverPage},
+			{Data: generated},
+			{Data: attachment, Pages: gpdf.PageRange{From: 1, To: 3}}, // only first 3 pages
+		},
+		gpdf.WithMergeMetadata("Policy Bundle", "Example Ltd", ""),
+	)
+	if err != nil {
+		t.Fatalf("Merge: %v", err)
+	}
+
+	testutil.AssertValidPDF(t, merged)
+	testutil.WritePDF(t, "05_issue11_example.pdf", merged)
+}
diff --git a/_validation/go.mod b/_validation/go.mod
index 43e6710..26a11bd 100644
--- a/_validation/go.mod
+++ b/_validation/go.mod
@@ -10,8 +10,8 @@ require (
 )
 
 require (
-	github.com/hhrutter/lzw v1.0.0 // indirect
-	github.com/hhrutter/tiff v1.0.1 // indirect
+	github.com/hhrutter/lzw v1.0.2 // indirect
+	github.com/hhrutter/tiff v1.0.2 // indirect
 	github.com/mattn/go-runewidth v0.0.16 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
diff --git a/_validation/go.sum b/_validation/go.sum
index c641ca2..7482956 100644
--- a/_validation/go.sum
+++ b/_validation/go.sum
@@ -1,7 +1,7 @@
-github.com/hhrutter/lzw v1.0.0 h1:laL89Llp86W3rRs83LvKbwYRx6INE8gDn0XNb1oXtm0=
-github.com/hhrutter/lzw v1.0.0/go.mod h1:2HC6DJSn/n6iAZfgM3Pg+cP1KxeWc3ezG8bBqW5+WEo=
-github.com/hhrutter/tiff v1.0.1 h1:MIus8caHU5U6823gx7C6jrfoEvfSTGtEFRiM8/LOzC0=
-github.com/hhrutter/tiff v1.0.1/go.mod h1:zU/dNgDm0cMIa8y8YwcYBeuEEveI4B0owqHyiPpJPHc=
+github.com/hhrutter/lzw v1.0.2 h1:laL89Llp86W3rRs83LvKbwYRx6INE8gDn0XNb1oXtm0=
+github.com/hhrutter/lzw v1.0.2/go.mod h1:2HC6DJSn/n6iAZfgM3Pg+cP1KxeWc3ezG8bBqW5+WEo=
+github.com/hhrutter/tiff v1.0.2 h1:MIus8caHU5U6823gx7C6jrfoEvfSTGtEFRiM8/LOzC0=
+github.com/hhrutter/tiff v1.0.2/go.mod h1:zU/dNgDm0cMIa8y8YwcYBeuEEveI4B0owqHyiPpJPHc=
 github.com/mattn/go-runewidth v0.0.16 h1:E5ScNMtiwvlvB5paMFdw9p4kSQzbXFikJ5SQO6TULQc=
 github.com/mattn/go-runewidth v0.0.16/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
 github.com/pdfcpu/pdfcpu v0.9.1 h1:q8/KlBdHjkE7ZJU4ofhKG5Rjf7M6L324CVM6BMDySao=
diff --git a/gpdf.go b/gpdf.go
index 7587563..1118c4c 100644
--- a/gpdf.go
+++ b/gpdf.go
@@ -151,6 +151,83 @@ func Open(data []byte, opts ...template.Option) (*template.ExistingDocument, err
 	return template.OpenExisting(data, opts...)
 }
 
+// ---------------------------------------------------------------------------
+// PDF Merge
+// ---------------------------------------------------------------------------
+
+// PageRange specifies a 1-based inclusive range of pages.
+// Zero values mean "from start" / "to end".
+type PageRange struct {
+	From int // 1-based; 0 means first page
+	To   int // 1-based; 0 means last page
+}
+
+// Source represents one input PDF in a merge operation.
+type Source struct {
+	Data  []byte    // raw PDF bytes
+	Pages PageRange // which pages to include; zero value = all pages
+}
+
+// MergeOption configures the merge operation.
+type MergeOption func(*mergeConfig)
+
+type mergeConfig struct {
+	title    string
+	author   string
+	producer string
+}
+
+// WithMergeMetadata sets the document info on the merged output.
+func WithMergeMetadata(title, author, producer string) MergeOption {
+	return func(c *mergeConfig) {
+		c.title = title
+		c.author = author
+		c.producer = producer
+	}
+}
+
+// Merge combines pages from multiple PDF sources into a single PDF.
+//
+//	merged, err := gpdf.Merge(
+//	    []gpdf.Source{
+//	        {Data: coverPage},
+//	        {Data: generated},
+//	        {Data: attachment, Pages: gpdf.PageRange{From: 1, To: 3}},
+//	    },
+//	    gpdf.WithMergeMetadata("Policy Bundle", "Example Ltd", ""),
+//	)
+func Merge(sources []Source, opts ...MergeOption) ([]byte, error) {
+	cfg := mergeConfig{producer: "gpdf " + Version}
+	for _, opt := range opts {
+		opt(&cfg)
+	}
+
+	pdfSources := make([]pdf.MergeSource, len(sources))
+	for i, s := range sources {
+		from := s.Pages.From - 1
+		if s.Pages.From <= 0 {
+			from = 0
+		}
+		to := s.Pages.To - 1
+		if s.Pages.To <= 0 {
+			to = -1
+		}
+		pdfSources[i] = pdf.MergeSource{
+			Data:     s.Data,
+			FromPage: from,
+			ToPage:   to,
+		}
+	}
+
+	return pdf.MergePDFs(pdfSources, pdf.MergeConfig{
+		Info: pdf.DocumentInfo{
+			Title:    cfg.title,
+			Author:   cfg.author,
+			Producer: cfg.producer,
+		},
+	})
+}
+
 // NewDocumentFromJSON is an alias for FromJSON that creates a Document
 // from a JSON schema, optionally resolving Go template expressions with data.
 func NewDocumentFromJSON(schema []byte, data any, opts ...template.Option) (*template.Document, error) {
diff --git a/pdf/merger.go b/pdf/merger.go
new file mode 100644
index 0000000..bdbda09
--- /dev/null
+++ b/pdf/merger.go
@@ -0,0 +1,190 @@
+package pdf
+
+import (
+	"bytes"
+	"fmt"
+)
+
+// MergeSource represents one input PDF in a merge operation.
+type MergeSource struct {
+	Data     []byte // raw PDF bytes
+	FromPage int    // 0-based inclusive start page
+	ToPage   int    // 0-based inclusive end page; -1 means last page
+}
+
+// MergeConfig configures the merge operation.
+type MergeConfig struct {
+	Info DocumentInfo
+}
+
+// MergePDFs combines pages from multiple PDF sources into a single PDF.
+func MergePDFs(sources []MergeSource, cfg MergeConfig) ([]byte, error) {
+	if len(sources) == 0 {
+		return nil, fmt.Errorf("pdf: merge requires at least one source")
+	}
+
+	var buf bytes.Buffer
+	w := NewWriter(&buf)
+	w.SetInfo(cfg.Info)
+
+	for i, src := range sources {
+		reader, err := NewReader(src.Data)
+		if err != nil {
+			return nil, fmt.Errorf("pdf: source %d: %w", i, err)
+		}
+
+		pageCount, err := reader.PageCount()
+		if err != nil {
+			return nil, fmt.Errorf("pdf: source %d: %w", i, err)
+		}
+
+		from := src.FromPage
+		to := src.ToPage
+		if to < 0 {
+			to = pageCount - 1
+		}
+
+		if from < 0 || from >= pageCount {
+			return nil, fmt.Errorf("pdf: source %d: from page %d out of range [0, %d)", i, from, pageCount)
+		}
+		if to < from || to >= pageCount {
+			return nil, fmt.Errorf("pdf: source %d: to page %d out of range [%d, %d)", i, to, from, pageCount)
+		}
+
+		mapper := newObjectMapper(reader)
+		for p := from; p <= to; p++ {
+			if err := mapper.copyPage(p, w); err != nil {
+				return nil, fmt.Errorf("pdf: source %d, page %d: %w", i, p, err)
+			}
+		}
+	}
+
+	if err := w.Close(); err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
+// objectMapper tracks object number remapping from one source PDF to the output.
+type objectMapper struct {
+	reader  *Reader
+	mapping map[int]int // source obj number -> output obj number
+}
+
+func newObjectMapper(r *Reader) *objectMapper {
+	return &objectMapper{
+		reader:  r,
+		mapping: make(map[int]int, r.MaxObjectNumber()),
+	}
+}
+
+// copyPage copies the i-th page from the source PDF into the writer.
+func (m *objectMapper) copyPage(pageIndex int, w *Writer) error {
+	pageDict, err := m.reader.PageDict(pageIndex)
+	if err != nil {
+		return err
+	}
+
+	// Deep copy the page dict, remapping all object references.
+	copied, err := m.copyObject(pageDict, w)
+	if err != nil {
+		return err
+	}
+
+	dict := copied.(Dict)
+
+	// Replace /Parent with the output page tree.
+	delete(dict, Name("Parent"))
+	dict[Name("Type")] = Name("Page")
+	dict[Name("Parent")] = w.PageTreeRef()
+
+	// Allocate and write the page object.
+	pageRef := w.AllocObject()
+	if err := w.WriteObject(pageRef, dict); err != nil {
+		return err
+	}
+	w.AddRawPage(pageRef)
+	return nil
+}
+
+// copyObject recursively copies a PDF object, remapping all indirect references
+// to new object numbers in the output writer.
+func (m *objectMapper) copyObject(obj Object, w *Writer) (Object, error) {
+	switch v := obj.(type) {
+	case ObjectRef:
+		return m.copyRef(v, w)
+	case Dict:
+		return m.copyDict(v, w)
+	case Array:
+		return m.copyArray(v, w)
+	case Stream:
+		return m.copyStream(v, w)
+	default:
+		// Integer, Real, Boolean, Name, LiteralString, HexString, Null, Rectangle
+		return obj, nil
+	}
+}
+
+func (m *objectMapper) copyRef(ref ObjectRef, w *Writer) (ObjectRef, error) {
+	// Already mapped?
+	if newNum, ok := m.mapping[ref.Number]; ok {
+		return ObjectRef{Number: newNum}, nil
+	}
+
+	// Allocate new object number before recursing (handles cycles).
+	newRef := w.AllocObject()
+	m.mapping[ref.Number] = newRef.Number
+
+	// Resolve the source object.
+	resolved, err := m.reader.GetObject(ref.Number)
+	if err != nil {
+		return ObjectRef{}, fmt.Errorf("resolve object %d: %w", ref.Number, err)
+	}
+
+	// Deep copy the resolved object.
+	copied, err := m.copyObject(resolved, w)
+	if err != nil {
+		return ObjectRef{}, err
+	}
+
+	// Write to output.
+	if err := w.WriteObject(newRef, copied); err != nil {
+		return ObjectRef{}, err
+	}
+	return newRef, nil
+}
+
+func (m *objectMapper) copyDict(d Dict, w *Writer) (Dict, error) {
+	newDict := make(Dict, len(d))
+	for key, val := range d {
+		copied, err := m.copyObject(val, w)
+		if err != nil {
+			return nil, err
+		}
+		newDict[key] = copied
+	}
+	return newDict, nil
+}
+
+func (m *objectMapper) copyArray(a Array, w *Writer) (Array, error) {
+	newArr := make(Array, len(a))
+	for i, item := range a {
+		copied, err := m.copyObject(item, w)
+		if err != nil {
+			return nil, err
+		}
+		newArr[i] = copied
+	}
+	return newArr, nil
+}
+
+func (m *objectMapper) copyStream(s Stream, w *Writer) (Stream, error) {
+	newDict, err := m.copyDict(s.Dict, w)
+	if err != nil {
+		return Stream{}, err
+	}
+	// Copy content bytes verbatim (no decompression/recompression).
+	content := make([]byte, len(s.Content))
+	copy(content, s.Content)
+	return Stream{Dict: newDict, Content: content}, nil
+}
diff --git a/pdf/merger_test.go b/pdf/merger_test.go
new file mode 100644
index 0000000..d00f2bd
--- /dev/null
+++ b/pdf/merger_test.go
@@ -0,0 +1,162 @@
+package pdf
+
+import (
+	"testing"
+)
+
+func TestMergeTwoPDFs(t *testing.T) {
+	pdf1 := buildTestPDF(t, 2)
+	pdf2 := buildTestPDF(t, 3)
+
+	merged, err := MergePDFs([]MergeSource{
+		{Data: pdf1, FromPage: 0, ToPage: -1},
+		{Data: pdf2, FromPage: 0, ToPage: -1},
+	}, MergeConfig{})
+	if err != nil {
+		t.Fatalf("MergePDFs: %v", err)
+	}
+
+	r, err := NewReader(merged)
+	if err != nil {
+		t.Fatalf("NewReader on merged: %v", err)
+	}
+	count, err := r.PageCount()
+	if err != nil {
+		t.Fatalf("PageCount: %v", err)
+	}
+	if count != 5 {
+		t.Errorf("PageCount = %d, want 5", count)
+	}
+}
+
+func TestMergePageRange(t *testing.T) {
+	pdf1 := buildTestPDF(t, 5)
+
+	merged, err := MergePDFs([]MergeSource{
+		{Data: pdf1, FromPage: 1, ToPage: 3}, // pages 2-4 (0-based)
+	}, MergeConfig{})
+	if err != nil {
+		t.Fatalf("MergePDFs: %v", err)
+	}
+
+	r, err := NewReader(merged)
+	if err != nil {
+		t.Fatalf("NewReader on merged: %v", err)
+	}
+	count, err := r.PageCount()
+	if err != nil {
+		t.Fatalf("PageCount: %v", err)
+	}
+	if count != 3 {
+		t.Errorf("PageCount = %d, want 3", count)
+	}
+}
+
+func TestMergeEmptySources(t *testing.T) {
+	_, err := MergePDFs(nil, MergeConfig{})
+	if err == nil {
+		t.Error("expected error for empty sources")
+	}
+}
+
+func TestMergeSingleSource(t *testing.T) {
+	pdf1 := buildTestPDF(t, 3)
+
+	merged, err := MergePDFs([]MergeSource{
+		{Data: pdf1, FromPage: 0, ToPage: -1},
+	}, MergeConfig{})
+	if err != nil {
+		t.Fatalf("MergePDFs: %v", err)
+	}
+
+	r, err := NewReader(merged)
+	if err != nil {
+		t.Fatalf("NewReader on merged: %v", err)
+	}
+	count, err := r.PageCount()
+	if err != nil {
+		t.Fatalf("PageCount: %v", err)
+	}
+	if count != 3 {
+		t.Errorf("PageCount = %d, want 3", count)
+	}
+}
+
+func TestMergeWithMetadata(t *testing.T) {
+	pdf1 := buildTestPDF(t, 1)
+
+	merged, err := MergePDFs([]MergeSource{
+		{Data: pdf1, FromPage: 0, ToPage: -1},
+	}, MergeConfig{
+		Info: DocumentInfo{Title: "Test Title", Author: "Test Author"},
+	})
+	if err != nil {
+		t.Fatalf("MergePDFs: %v", err)
+	}
+
+	r, err := NewReader(merged)
+	if err != nil {
+		t.Fatalf("NewReader on merged: %v", err)
+	}
+
+	// Verify the Info dict exists in the trailer.
+	infoObj, ok := r.Trailer()[Name("Info")]
+	if !ok {
+		t.Fatal("merged PDF has no /Info in trailer")
+	}
+	infoDict, err := r.ResolveDict(infoObj)
+	if err != nil {
+		t.Fatalf("resolve Info: %v", err)
+	}
+	if title, ok := infoDict[Name("Title")]; !ok {
+		t.Error("Info dict missing /Title")
+	} else if title.(LiteralString) != "Test Title" {
+		t.Errorf("Title = %v, want 'Test Title'", title)
+	}
+}
+
+func TestMergeInvalidPageRange(t *testing.T) {
+	pdf1 := buildTestPDF(t, 2)
+
+	_, err := MergePDFs([]MergeSource{
+		{Data: pdf1, FromPage: 0, ToPage: 5},
+	}, MergeConfig{})
+	if err == nil {
+		t.Error("expected error for out-of-range page")
+	}
+}
+
+func TestMergeRoundTrip(t *testing.T) {
+	// Merge, read, merge again to verify output is valid PDF.
+	pdf1 := buildTestPDF(t, 2)
+	pdf2 := buildTestPDF(t, 1)
+
+	merged1, err := MergePDFs([]MergeSource{
+		{Data: pdf1, FromPage: 0, ToPage: -1},
+		{Data: pdf2, FromPage: 0, ToPage: -1},
+	}, MergeConfig{})
+	if err != nil {
+		t.Fatalf("first merge: %v", err)
+	}
+
+	// Merge the merged PDF with another.
+	merged2, err := MergePDFs([]MergeSource{
+		{Data: merged1, FromPage: 0, ToPage: -1},
+		{Data: pdf2, FromPage: 0, ToPage: -1},
+	}, MergeConfig{})
+	if err != nil {
+		t.Fatalf("second merge: %v", err)
+	}
+
+	r, err := NewReader(merged2)
+	if err != nil {
+		t.Fatalf("NewReader on double-merged: %v", err)
+	}
+	count, err := r.PageCount()
+	if err != nil {
+		t.Fatalf("PageCount: %v", err)
+	}
+	if count != 4 {
+		t.Errorf("PageCount = %d, want 4", count)
+	}
+}
diff --git a/pdf/writer.go b/pdf/writer.go
index 8e0a26e..25128c5 100644
--- a/pdf/writer.go
+++ b/pdf/writer.go
@@ -152,6 +152,18 @@ func (pw *Writer) AddPage(page PageObject) error {
 	return nil
 }
 
+// AddRawPage registers a pre-written page object reference in the page tree.
+// The caller is responsible for writing the page dict with the correct /Parent.
+func (pw *Writer) AddRawPage(ref ObjectRef) {
+	pw.pages = append(pw.pages, ref)
+}
+
+// PageTreeRef returns the page tree object reference.
+// This is used as the /Parent value for pages added via AddRawPage.
+func (pw *Writer) PageTreeRef() ObjectRef {
+	return pw.pageTree
+}
+
 // ReserveFontRef reserves a font resource name and object reference for the
 // given font name without writing any PDF objects. This allows Type0/CIDFont
 // structures to be written later via OnBeforeClose hooks.