Python · FastAPI

Authentication for FastAPI

A session resolver, a require_auth gate, and a logout handler for FastAPI, delivered as first-class dependencies that return a typed AuthdogContext. Validate Authdog sessions on every request, on the same wire as the Node SDKs.

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PyPI

CI passing

One dependency: Add authdog.session as a dependency and any path operation gets a typed AuthdogContext. No middleware boilerplate.
One enforcement point: Depend on authdog.require_auth and unauthenticated requests are rejected with 401 before your handler runs.
Non-blocking by default: Session resolution runs on the event loop with an async httpx client, so gating a route never blocks the worker.
At most one userinfo call: The context is cached on request.state, so composing session and require_auth costs a single lookup.

Add the dependency

12345678# main.py
from authdog.fastapi import Authdog

authdog = Authdog(public_key=os.environ["PK_AUTHDOG"])

@app.get("/")
async def index(ctx=Depends(authdog.session)):
    return {"authenticated": ctx.is_authenticated}

Gate routes with require_auth

1234# routes.py
@app.get("/me")
async def me(user=Depends(authdog.require_auth)):
    return user

Dependencies, not middleware

Everything FastAPI apps need

A drop-in session resolver, a require_auth gate, and a typed context, all expressed as FastAPI dependencies you compose, override, and test like any other.

A FastAPI dependency

Depends(authdog.session) resolves the request's session and returns a typed AuthdogContext with token, user, and is_authenticated for any path operation.

Typed AuthdogContext
Any path operation

require_auth gate

Depend on authdog.require_auth and FastAPI raises HTTPException(401) for unauthenticated requests, returning the user object otherwise. This is the security boundary.

401 before your handler
Returns the verified user

At most one userinfo call

The resolved context is cached on request.state, so combining session and require_auth on one request makes a single outbound userinfo call.

Cached on request.state
One outbound call

Native to the dependency system

The bindings are plain FastAPI dependencies. Compose them with your own Depends(), override them in tests, and document them automatically in /docs.

Override in tests
Documented in /docs

Safe logout handler

authdog.logout(request) returns a RedirectResponse that expires the session cookie and redirects to a redirect_uri sanitized against open redirects.

Expires the cookie
Open-redirect safe

Same wire as Node

It mirrors @authdog/express and @authdog/fastify on the wire, so one Authdog environment serves your Node and FastAPI services interchangeably.

One environment
Node and Python together

Install

pip install 'authdog-fastapi[fastapi]'.

Create the client

Instantiate Authdog with your environment's public key.

Gate routes

Depend on require_auth where a user is required.

Add auth to your FastAPI app.

pip install 'authdog-fastapi[fastapi]', wire up the dependency, and gate your routes with require_auth today. Free to start, with secure defaults built in.

Start Building