FastAPI Skill for Claude Code: Official Best Practices

Makes Claude write modern FastAPI code the way the FastAPI project recommends, for anyone building or maintaining a FastAPI API.

Installs: 14.2K; on skills.sh
Stars: 104.5K; on GitHub
Files: 6; besides SKILL.md
Updated: Nov 2026; last repo commit

fastapi is a skill that ships inside the FastAPI repository itself. It makes Claude follow current FastAPI conventions: Annotated parameters and dependencies, return types instead of ORJSONResponse, routers that carry their own prefix and tags, and one function per HTTP operation. It also covers newer features such as app.frontend(), Server-Sent Events and built-in OpenTelemetry.

It triggers when you work on FastAPI APIs, Pydantic models, dependencies, streaming or frontend serving. It bundles six reference guides and no scripts. It tells Claude to use the fastapi CLI, and to prefer uv, Ruff, ty, Asyncer, SQLModel and HTTPX where they fit.

Good for

Python developers building APIs with FastAPI and Pydantic
Teams whose AI-written FastAPI code uses old patterns
Developers adding SSE streaming, OpenTelemetry or a bundled frontend

Install fastapi

Claude Code

Copy this prompt.

Install the fastapi skill in Claude Code. Run this command:

npx skills add https://github.com/fastapi/fastapi --skill fastapi

Then check that it loaded and tell me how to use it.

2
Paste it into Claude Code. It shows the change and asks before running it.

Requires Node.js.

From its listing on skills.sh. Source.

What's in the skill

When it loads

FastAPI best practices and conventions. Use when working with FastAPI APIs, Pydantic models, dependencies, streaming responses including Server-Sent Events (SSE), and serving frontend apps. Keeps FastAPI code clean and up to date with the latest features and patterns.

Sections in SKILL.md

Quick Reference
Use the fastapi CLI
Use Annotated
Do not use Ellipsis for path operations or Pydantic models
Return Type or Response Model
Performance
Including Routers
Serve Frontend Apps
OpenTelemetry
Dependency Injection
Async vs Sync path operations
Streaming (JSON Lines, SSE, bytes)
Tooling
Other Libraries
Do not use Pydantic RootModels
Use one HTTP operation per function

Key facts

Author: FastAPI (fastapi/fastapi repo)
Repository: fastapi/fastapi
Installs on skills.sh: 14,162 as of 2026-11-02
GitHub stars: 104,535 for the whole fastapi/fastapi repo
License: MIT (repo LICENSE)
Last repo commit: 2026-11-01
What is inside: 7 files including SKILL.md: SKILL.md and 6 reference guides (dependencies, other tools, path operations, pydantic, responses, streaming). It bundles no scripts.
Location: fastapi/.agents/skills/fastapi inside the main FastAPI repo; SKILL.md calls it the "Official FastAPI skill"

What it includes

fastapi dev to develop, fastapi run for production
Prefers declaring the entrypoint under [tool.fastapi] in pyproject.toml. A file path is passed only when that is not possible or you ask.
Try: “Add a /items endpoint with a Pydantic model and a shared auth dependency using the fastapi skill.”
Runs code · fastapi CLI
Annotated for Path, Query, Header and Depends
Create a type alias for each dependency so it can be reused.
Annotated style
Required fields have no ... default; use plain annotations
Do not use ... for required parameters or model fields, and do not use Pydantic RootModel.
No Ellipsis, no RootModel
Declare return types; response_model when the public shape differs
Return types validate, filter, document and serialize the response. ORJSONResponse and UJSONResponse are called deprecated.
Return types and response_model
Prefix, tags and dependencies go on the APIRouter
Set them on the router, not in include_router().
Routers
Serve a built Vite, Astro, Vue or similar frontend
Use app.frontend("/", directory="dist") or router.frontend() instead of mounting StaticFiles by hand. API routes match first.
app.frontend()
Native traces, metrics and logs via fastapi[standard]
Set FASTAPI_OTEL_AUTO_CONFIGURE=true, OTEL_SERVICE_NAME and OTEL_EXPORTER_OTLP_ENDPOINT, plus OTEL_EXPORTER_OTLP_HEADERS if the collector needs auth.
Network · OpenTelemetry
Annotated Depends, yield with scope, class dependencies
Apply shared dependencies at the router level. Details are in references/dependencies.md.
Dependency injection
Plain def by default; async only when sure nothing blocks
Regular def functions run in a threadpool. Blocking code inside async functions hurts performance.
Async vs sync
JSON Lines, Server-Sent Events and byte streams
Use response_class=EventSourceResponse and yield items for SSE. ServerSentEvent gives control over event, id, retry and comment fields.
Streaming
uv, Ruff, ty, Asyncer, SQLModel, HTTPX
Use uv for dependencies, Asyncer to mix blocking and async code, SQLModel over SQLAlchemy and HTTPX over Requests. The guide shows uv add asyncer.
Runs code · Other tools
Do not mix GET and POST in one function
Keeps concerns separate and code easier to organize.
One operation per function

From the official docs

Permissions

Low risk

The skill bundles no scripts, but it tells Claude to run the fastapi CLI and uv in your project.

What it can do

Read your data
Create and change things
Delete things
Read-only mode

Watch out for

It suggests running servers and installing packages
fastapi dev starts a local server and uv add installs a package. Approve these commands like any other. github.com

Security advisories

No published security advisories as of Nov 2, 2026.

Technical details

Turning on read-only	No read-only mode is described. The skill bundles SKILL.md and 6 reference files and no scripts.
Talks to	OpenTelemetry settings point the app at a collector URL you set
Sign-in and keys	SKILL.md mentions OTEL_EXPORTER_OTLP_HEADERS for collector auth, which you set yourself.
Data retention	Not described in SKILL.md.
Scopes	Claude edits your FastAPI code Claude may run fastapi dev, fastapi run and uv add in your project

Questions

What does the FastAPI skill do?

It makes Claude write FastAPI code using the conventions in the FastAPI repo, such as Annotated dependencies, return types, router-level settings, SSE streaming and OpenTelemetry. It is meant to keep generated code current with new FastAPI versions.

How do I install the FastAPI skill?

Use the install box at the top of this page. It copies the skill folder from the fastapi/fastapi repo. The folder sits at fastapi/.agents/skills/fastapi.

Is it the official FastAPI skill?

The SKILL.md calls itself the "Official FastAPI skill", and it lives in the main FastAPI repository.

Does it need a specific FastAPI version?

SKILL.md states no version number. It covers features such as app.frontend() and EventSourceResponse, which are newer parts of FastAPI, so check your installed version supports them.

Does it work in Cursor, Codex or Claude.ai?

SKILL.md does not list clients. The skill is a folder of Markdown files, so check your tool's skills docs for how it loads skills.

Is it safe?

It bundles no scripts. It tells Claude to run commands such as fastapi dev and uv add in your project, so approve each command as you would any other. The fastapi dev server runs on localhost.

Information

updated Nov 2, 2026

Repository: fastapi/fastapi
Folder: fastapi/.agents/skills/fastapi

fastapi/fastapi skills.sh

Sources

Docs, issue trackers and discussions this page is built from.

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