Tooling

A tour of the tools and scripts that surround the framework code.

Build system

• PDM backend. pyproject.toml [build-system] uses pdm-backend. The version is read from fastapi/__init__.py (see [tool.pdm.version]).
• uv lockfile. uv.lock is committed (1 MB). Either uv sync or pdm install -G:all produces a working dev environment.
• fastapi-slim distribution. The fastapi-slim/ directory hosts an alternate pyproject.toml that builds the same code under a different package name with different default extras. CI builds both; .github/workflows/test-redistribute.yml exercises them.

Lint and format

scripts/lint.sh:

mypy fastapi
ty check fastapi
ruff check fastapi tests docs_src scripts
ruff format fastapi tests --check

scripts/format.sh:

ruff check fastapi tests docs_src scripts --fix
ruff format fastapi tests docs_src scripts

scripts/lint.sh formats only fastapi and tests, while format.sh extends formatting to docs_src and scripts. Lint configuration lives in pyproject.toml under tool.ruff.* and tool.mypy.*.

prek (a Rust-based pre-commit-compatible runner) is in the dev dependency group; CI runs pre-commit.yml to validate hooks.

Testing helpers

Script	Purpose
scripts/test.sh	Run pytest with PYTHONPATH=./docs_src and -n auto --dist loadgroup.
scripts/test-cov.sh	Run tests under coverage; print combined report.
scripts/test-cov-html.sh	Same, but emit an HTML report.
scripts/coverage.sh	Run coverage combine + coverage report.

Documentation tooling

scripts/docs.py is a Typer CLI for everything documentation-related:

Sub-command	What it does
live	Run MkDocs serve. Optional language argument (live es).
build-all	Build every language under docs/.
preview	Serve a previously built site.
serve	Alternate dev server.
verify-config	Validate per-language mkdocs.yml.
update-languages	Refresh per-language config files from English.
verify-non-translated	Check that English-only files exist as expected.

It plays well with MkDocs Material insiders when present and falls back to the OSS build otherwise. Hooks live in scripts/mkdocs_hooks.py.

Translation tooling

Script	Purpose
scripts/translate.py	LLM-driven translation pipeline using pydantic-ai. Provides commands to translate individual pages or batches and to record progress in tracking issues.
scripts/notify_translations.py	Posts comments on tracking GitHub issues when a page changes in English. Triggered by .github/workflows/notify-translations.yml.
scripts/translation_fixer.py	Bulk-edit fixer for translation discrepancies.
scripts/people.py	Refreshes the contributors / experts / translators pages from GitHub data.
scripts/sponsors.py	Refreshes the sponsors section in README.md and the docs site.
scripts/topic_repos.py	Maintains the list of community repos tagged with the fastapi topic.
scripts/contributors.py	Powers the contributors workflow alongside people.py.
scripts/deploy_docs_status.py	Posts the docs preview deployment status to the PR.
scripts/label_approved.py	Labels PRs that have approving reviews.
scripts/add_latest_release_date.py	Stamps the release-notes header with a date.

These scripts are wired into workflows under .github/workflows/:

• people.yml, contributors.yml, sponsors.yml, topic-repos.yml rebuild auto-generated content.
• translate.yml, notify-translations.yml keep translations in sync.
• latest-changes.yml regenerates release notes from merged PRs.
• label-approved.yml, labeler.yml automate triage.

Tests for the scripts

scripts/tests/ contains pytest tests for the larger automation scripts (notably scripts/docs.py). scripts/test.sh runs them as part of the regular suite (pytest tests scripts/tests/).

Playwright

tests/ does not currently use Playwright, but playwright >= 1.57.0 is in the dev group and scripts/playwright/ contains scripted browser interactions used to maintain the docs site (e.g., automated screenshots).

CI

See Development workflow / CI surface. The most important workflow for changes to the framework itself is test.yml; the most important for docs is build-docs.yml and deploy-docs.yml; the most important for the slim distribution is test-redistribute.yml.