openapi-lens 1.0.0

OpenAPI snapshot tracking and visual diff tool for FastAPI projects

ApiLens

OpenAPI snapshot tracking and visual diff for FastAPI projects.

ApiLens automatically captures versioned snapshots of your OpenAPI spec on every merge, provides a visual diff viewer, and posts PR comments summarizing what changed.

Features

• Automatic snapshots — captures your spec on every merge to main; skips if nothing changed
• Visual diff viewer — color-coded UI showing new, removed, and modified endpoints with field-level detail
• PR comments — posts a Markdown summary of API changes on every pull request
• AI prompts — one-click copy of prompts to help update frontend TypeScript types
• Zero integration — no changes needed to your FastAPI app; runs standalone

Install

pip install api-lens[serve]

Quick Start

1. Create apilens.toml

[apilens]
app = "myapp.main:app"        # dotted path to your FastAPI app object
snapshots_dir = "openapi-snapshots"

2. Generate a snapshot manually

apilens snapshot

3. Browse the diff viewer

apilens serve
# → http://127.0.0.1:8765

Optionally password-protect it:

APILENS_PASSWORD=secret apilens serve

4. Add to CI

Copy the workflow templates from .github/workflows/ into your repo. They require no secrets beyond the built-in GITHUB_TOKEN.

CLI Reference

apilens generate <output>    Write the current OpenAPI spec to a JSON file
apilens snapshot             Write a snapshot (skips if spec unchanged)
apilens serve                Start the visual diff viewer

Disabling the PR Comment

To temporarily disable the PR comment without deleting the workflow:

# In .github/workflows/api-diff.yml, change:
if: github.event_name == 'pull_request'
# to:
if: false && github.event_name == 'pull_request'

Remove the false && to re-enable.

License

MIT