auth0-fastapi-api
Use when protecting FastAPI endpoints with JWT Bearer token validation, scope checks, or DPoP binding. Integrates auth0-fastapi-api for stateless APIs receiving access tokens — use even if the user says "secure my FastAPI endpoints" or "validate tokens in FastAPI".
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/auth0/agent-skills --skill auth0-fastapi-api- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads auth0-fastapi-api automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
Auth0 FastAPI API Integration
Protect FastAPI API endpoints with JWT access token validation using auth0-fastapi-api.
Note: This SDK is currently in beta. The API surface may change before the stable 1.0 release. Check PyPI for the latest version. Requires Python >= 3.9 and FastAPI >= 0.115.11.
Prerequisites
- FastAPI application (Python 3.9+)
- Auth0 API resource configured (not an Application — must be an API)
- If you don't have Auth0 set up yet, use the
auth0-quickstartskill first
When NOT to Use
- Server-rendered web applications — Use a session-based login/logout flow instead
- Single Page Applications — Use
auth0-react,auth0-vue, orauth0-angularfor client-side auth - Mobile applications — Use
auth0-react-nativeorauth0-android - Issuing tokens — This skill is for validating access tokens, not issuing them
Quick Start Workflow
1. Install SDK
pip install auth0-fastapi-api python-dotenv
2. Create Auth0 API
You need an API (not Application) in Auth0.
STOP — ask the user before proceeding.
Ask exactly this question and wait for their answer before doing anything else:
"How would you like to create the Auth0 API resource?
- Automated — I'll run Auth0 CLI scripts that create the resource and write the exact values to your
.envautomatically.- Manual — You create the API yourself in the Auth0 Dashboard (or via
auth0 apis create) and provide me the Domain and Audience.Which do you prefer? (1 = Automated / 2 = Manual)"
Do NOT proceed to any setup steps until the user has answered. Do NOT default to manual.
If the user chose Automated, follow the Setup Guide for complete CLI scripts. The automated path writes .env for you — skip Step 3 below and proceed directly to Step 4.
If the user chose Manual, follow the Setup Guide (Manual Setup section) for full instructions. Then continue with Step 3 below.
Quick reference for manual API creation:
# Using Auth0 CLI
auth0 apis create \
--name "My FastAPI API" \
--identifier https://my-api.example.com
Or create manually in Auth0 Dashboard → Applications → APIs
3. Configure Environment
Create .env:
AUTH0_DOMAIN=your-tenant.us.auth0.com
AUTH0_AUDIENCE=https://your-api.example.com
AUTH0_DOMAIN is your Auth0 tenant domain (without https://). AUTH0_AUDIENCE is the API identifier you set when creating the API resource in Auth0.
4. Initialize Auth0
import os
from fastapi import FastAPI, Depends
from fastapi_plugin import Auth0FastAPI
from dotenv import load_dotenv
load_dotenv()
app = FastAPI()
auth0 = Auth0FastAPI(
domain=os.getenv("AUTH0_DOMAIN"),
audience=os.getenv("AUTH0_AUDIENCE"),
)
Create one Auth0FastAPI instance per application and reuse it across routes. Never hardcode the domain or audience — always use environment variables.
5. Protect Routes
# Require any valid access token
@app.get("/api/private")
async def private(claims: dict = Depends(auth0.require_auth())):
return {"user": claims["sub"]}
# No authentication required
@app.get("/api/public")
async def public():
return {"message": "Public endpoint"}
The require_auth() dependency validates the Bearer token, verifies the issuer and audience, and returns the decoded JWT claims.
Error responses:
- 400
invalid_request— Missing or malformed Authorization header - 401
invalid_token— Expired token, invalid signature, wrong issuer/audience - 403
insufficient_scope— Valid token but missing required scopes - 500
internal_server_error— Unexpected errors
Response body format: {"detail": {"error": "...", "error_description": "..."}}
6. Protect Routes with Scope Checks
# Requires the read:messages scope
@app.get("/api/messages")
async def get_messages(claims: dict = Depends(auth0.require_auth(scopes="read:messages"))):
return {"messages": []}
# Requires both read:data and write:data scopes
@app.post("/api/data")
async def write_data(claims: dict = Depends(auth0.require_auth(scopes=["read:data", "write:data"]))):
return {"created": True}
require_auth(scopes=...) checks the scope claim in the JWT. All specified scopes must be present (AND logic). Missing scopes return 403.
7. Access Token Claims
The decoded JWT claims are returned directly from the dependency:
@app.get("/api/profile")
async def profile(claims: dict = Depends(auth0.require_auth())):
return {
"sub": claims["sub"], # user ID
"scope": claims.get("scope"), # granted scopes
}
Key claims:
claims["sub"]— user/client IDclaims["scope"]— space-separated granted scopesclaims["iss"]— issuer (your Auth0 domain URL)claims["aud"]— audienceclaims["exp"]— expiration timestampclaims["iat"]— issued-at timestamp
8. Protect Routes Without Needing Claims
@app.get("/api/protected", dependencies=[Depends(auth0.require_auth())])
async def protected():
return {"message": "You need a valid access token to see this."}
9. Test the API
# No token — expect 401
curl http://localhost:8000/api/private
# With a valid access token
curl http://localhost:8000/api/private \
-H "Authorization: Bearer YOUR_ACCESS_TOKEN"
Get a test token via Client Credentials flow or Auth0 Dashboard → APIs → Test tab.
Common Mistakes
| Mistake | Fix |
|---|---|
Hardcoding domain or audience in source | Always read from environment variables — never embed credentials in code |
Using python-jose or PyJWT directly | Not needed; auth0-fastapi-api handles all validation via JWKS |
Manually parsing Authorization header | The SDK extracts and validates the token automatically |
Calling jwt.decode() manually | The SDK verifies tokens against the JWKS endpoint — do not verify yourself |
Using fastapi-users for Auth0 JWT validation | That package is for user management, not Auth0 JWT verification |
| Created an Application instead of an API in Auth0 | Must create an API resource (Applications → APIs) — an Application doesn't issue access tokens with the right audience |
Passing domain as full URL with https:// | domain should be the bare domain, e.g. my-tenant.us.auth0.com, not https://my-tenant.us.auth0.com |
| Using an ID token instead of an access token | Must use the access token for API auth — ID tokens are for the client app, not for API authorization |
| Not configuring CORS for SPA clients | Add CORSMiddleware to allow requests from your frontend origin |
os.getenv() returns None silently | Ensure python-dotenv is installed and load_dotenv() is called before Auth0FastAPI() initialization — or use os.environ[] to fail fast |
DPoP Support
Built-in proof-of-possession token binding per RFC 9449. DPoP is enabled by default in mixed mode (accepts both Bearer and DPoP tokens). See Integration Guide for configuration.
Related Skills
auth0-quickstart- Basic Auth0 setup and framework detectionauth0-mfa- Add Multi-Factor Authenticationauth0-cli- Manage Auth0 resources from the terminal
Quick Reference
Auth0FastAPI configuration:
auth0 = Auth0FastAPI(
domain=os.getenv("AUTH0_DOMAIN"), # required (or use domains)
audience=os.getenv("AUTH0_AUDIENCE"), # required
dpop_enabled=True, # default; set False for Bearer-only
dpop_required=False, # default; set True to reject Bearer tokens
)
Route protection:
Depends(auth0.require_auth()) # any valid token
Depends(auth0.require_auth(scopes="read:res")) # single scope
Depends(auth0.require_auth(scopes=["r", "w"])) # all scopes required
Accessing claims:
claims["sub"] # user/client ID
claims["scope"] # space-separated scopes
Environment variables:
AUTH0_DOMAIN— your Auth0 tenant domain (e.g.tenant.us.auth0.com)AUTH0_AUDIENCE— your API identifier (e.g.https://api.example.com)
Common Use Cases:
- Protect routes →
Depends(auth0.require_auth())(see Step 5) - Scope enforcement →
Depends(auth0.require_auth(scopes="..."))(see Step 6) - DPoP token binding → Integration Guide
- Reverse proxy setup → Integration Guide
- Advanced configuration → API Reference
Detailed Documentation
- Setup Guide — Auth0 CLI setup, environment configuration, getting test tokens
- Integration Guide — DPoP, scopes, error handling, reverse proxy, testing
- API Reference — Complete constructor options, method signatures, error codes
References
FAQ
What does the auth0-fastapi-api skill do?
Use when protecting FastAPI endpoints with JWT Bearer token validation, scope checks, or DPoP binding. Integrates auth0-fastapi-api for stateless APIs receiving access tokens — use even if the user says "secure my FastAPI endpoints" or "validate tokens in FastAPI".
How do I install auth0-fastapi-api?
Run npx skills add https://github.com/auth0/agent-skills --skill auth0-fastapi-api in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/auth0-fastapi-api/ (personal) or .claude/skills/auth0-fastapi-api/ (project).
Which AI agents can use auth0-fastapi-api?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is auth0-fastapi-api safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains auth0-fastapi-api?
It is published by auth0 in auth0/agent-skills, and it is an official skill from the maker of the technology it covers. It has 461 recorded installs.
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