fauth 0.5.5

Ergonomic, lightweight JWT authentication for FastAPI. Secure your routes instantly with plug-and-play dependency injection

FAuth

An ergonomic, plug-and-play authentication library for FastAPI.

fauth eliminates boilerplate around JWT, password hashing, user fetching, and Role-Based Access Control (RBAC) by leveraging FastAPI's Dependency Injection (Depends), Pydantic models, and Python Protocols.

Features

• Protocol-Based User Fetching — Complete inversion of control via UserLoader and IdentityLoader protocols.
• Plug-and-Play Configuration — Centralized settings via Pydantic (AuthConfig). Configure once, inject everywhere.
• Pluggable Transports — Extensible Transport protocol with a built-in BearerTransport.
• Automatic OpenAPI/Swagger UI Support — Integrated security schemes with "Authorize" button in Swagger UI.
• Built-in Password Hashing & JWT Crypto — Argon2 via pwdlib and utilities for creating/decoding access and refresh tokens.
• RBAC — require_roles and require_permissions dependencies with customizable user model field names.
• Secure Router — SecureAPIRouter secures all its routes automatically.
• Structured Logging — Built-in structlog-based logging.
• Type Safe — Fully annotated for MyPy and IDE integration.

Installation

pip install fauth

Or with uv:

uv add fauth

Quick Start

from pydantic import BaseModel
from fastapi import FastAPI, Depends
from fauth import AuthConfig, AuthProvider, TokenPayload, hash_password

class User(BaseModel):
    id: str
    username: str
    hashed_password: str
    is_active: bool = True
    roles: list[str] = []
    permissions: list[str] = []

DB: dict[str, User] = {
    "user-123": User(id="user-123", username="alice", hashed_password=hash_password("s3cret"), roles=["admin"]),
}

async def load_user(payload: TokenPayload) -> User | None:
    return DB.get(payload.sub)

async def load_identity(identifier: str) -> User | None:
    return next((u for u in DB.values() if u.username == identifier), None)

config = AuthConfig(secret_key="my-super-secret-key")
auth: AuthProvider[User] = AuthProvider(config=config, user_loader=load_user, identity_loader=load_identity)

app = FastAPI()

@app.post("/login")
async def login(username: str, password: str):
    user = await auth.authenticate(username, password)
    return await auth.login(sub=user.id)

@app.get("/me")
async def get_me(user: User = Depends(auth.require_user)):
    return {"message": f"Hello {user.username}"}

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:book: Full documentation at fauth.readthedocs.io

License

MIT