Specfly is Spec-Driven Development tooling. It builds on awesome OpenSpec to make working with LLMs efficient, and helps you run your specs in a safe environment with full control and and minimal setup on your end.
- 🛡️ Safe unattended runs. The agent runs in an ephemeral, isolated GitHub Actions environment.
- 💸 Cost control. Bring your own Anthropic key and run on your Github runner.
- 🧩 Open and composable. Supports any popular tech stack and drops into bigger workflows cleanly.
- 🥇Best practices. Stay efficient in the long run with spec-driven advantage.
A hosted Specfly control plane (a GitHub App + a tiny backend) dispatches work into your Actions runner. Cloning and running the Agent happens in your Actions on your Anthropic key. Specfly only routes the trigger and authors the PR. All your data stays in your environment at all times.
Because the PR is authored by Specfly[bot] (a separate actor), you can approve
it yourself and your CI still triggers. See the design overview for the full architecture and security model.
- Install the Specfly App at
github.com/apps/specfly(pick your repos). - Add one secret —
ANTHROPIC_API_KEY(bring your own key). - Add one caller workflow — see
examples/adopter-workflow.yml. - Copy one command file —
.claude/commands/sfx/apply.md; then/sfx:apply [<name>]triggers an apply. - (Recommended) Protect
main— require a PR + 1 approval, block direct pushes: Protectingmain.
Full walkthrough, the per-change usage flow, and how to fine-tune for your stack are in Getting started.
- Design overview — how Specfly is built and why.
- Getting started — full adopter setup and usage flow.
- Fine-tuning for your stack — environment provisioning on any toolchain.
- Protecting
main— the branch ruleset that keeps unreviewed code offmain. - Backend reference — control-plane engineering reference.
See the documentation index for the full map.
MIT © Foster Systems