---
title: Auth0 OAuth 🤝 FastMCP
sidebarTitle: Auth0
description: Secure your FastMCP server with Auth0 OAuth
icon: shield-check
tag: NEW
---

import { VersionBadge } from "/snippets/version-badge.mdx"

<VersionBadge version="2.12.4" />

This guide shows you how to secure your FastMCP server using **Auth0 OAuth**. While Auth0 does have support for Dynamic Client Registration, it is not enabled by default so this integration uses the [**OIDC Proxy**](/servers/auth/oidc-proxy) pattern to bridge Auth0's dynamic OIDC configuration with MCP's authentication requirements.

## Configuration

### Prerequisites

Before you begin, you will need:
1. An **[Auth0 Account](https://auth0.com/)** with access to create Applications
2. Your FastMCP server's URL (can be localhost for development, e.g., `http://localhost:8000`)

### Step 1: Create an Auth0 Application

Create an Application in your Auth0 settings to get the credentials needed for authentication:

<Steps>
<Step title="Navigate to Applications">
    Go to **Applications → Applications** in your Auth0 account.

    Click **"+ Create Application"** to create a new application.
</Step>

<Step title="Create Your Application">
    - **Name**: Choose a name users will recognize (e.g., "My FastMCP Server")
    - **Choose an application type**: Choose "Single Page Web Applications"
    - Click **Create** to create the application
</Step>

<Step title="Configure Your Application">
    Select the "Settings" tab for your application, then find the "Application URIs" section.

    - **Allowed Callback URLs**: Your server URL + `/auth/callback` (e.g., `http://localhost:8000/auth/callback`)
    - Click **Save** to save your changes

    <Warning>
    The callback URL must match exactly. The default path is `/auth/callback`, but you can customize it using the `redirect_path` parameter.
    </Warning>

    <Tip>
    If you want to use a custom callback path (e.g., `/auth/auth0/callback`), make sure to set the same path in both your Auth0 Application settings and the `redirect_path` parameter when configuring the Auth0Provider.
    </Tip>
</Step>

<Step title="Save Your Credentials">
    After creating the app, in the "Basic Information" section you'll see:

    - **Client ID**: A public identifier like `tv2ObNgaZAWWhhycr7Bz1LU2mxlnsmsB`
    - **Client Secret**: A private hidden value that should always be stored securely

    <Tip>
    Store these credentials securely. Never commit them to version control. Use environment variables or a secrets manager in production.
    </Tip>
</Step>

<Step title="Select Your Audience">
  Go to **Applications → APIs** in your Auth0 account.

    - Find the API that you want to use for your application
    - **API Audience**: A URL that uniquely identifies the API

    <Tip>
    Store this along with of the credentials above. Never commit this to version control. Use environment variables or a secrets manager in production.
    </Tip>
</Step>
</Steps>

### Step 2: FastMCP Configuration

Create your FastMCP server using the `Auth0Provider`.

```python server.py
from fastmcp import FastMCP
from fastmcp.server.auth.providers.auth0 import Auth0Provider

# The Auth0Provider utilizes Auth0 OIDC configuration
auth_provider = Auth0Provider(
    config_url="https://.../.well-known/openid-configuration",  # Your Auth0 configuration URL
    client_id="tv2ObNgaZAWWhhycr7Bz1LU2mxlnsmsB",               # Your Auth0 application Client ID
    client_secret="vPYqbjemq...",                               # Your Auth0 application Client Secret
    audience="https://...",                                     # Your Auth0 API audience
    base_url="http://localhost:8000",                           # Must match your application configuration
    # redirect_path="/auth/callback"                            # Default value, customize if needed
)

mcp = FastMCP(name="Auth0 Secured App", auth=auth_provider)

# Add a protected tool to test authentication
@mcp.tool
async def get_token_info() -> dict:
    """Returns information about the Auth0 token."""
    from fastmcp.server.dependencies import get_access_token

    token = get_access_token()

    return {
        "issuer": token.claims.get("iss"),
        "audience": token.claims.get("aud"),
        "scope": token.claims.get("scope")
    }
```

## Testing

### Running the Server

Start your FastMCP server with HTTP transport to enable OAuth flows:

```bash
fastmcp run server.py --transport http --port 8000
```

Your server is now running and protected by Auth0 authentication.

### Testing with a Client

Create a test client that authenticates with your Auth0-protected server:

```python test_client.py
from fastmcp import Client
import asyncio

async def main():
    # The client will automatically handle Auth0 OAuth flows
    async with Client("http://localhost:8000/mcp/", auth="oauth") as client:
        # First-time connection will open Auth0 login in your browser
        print("✓ Authenticated with Auth0!")

        # Test the protected tool
        result = await client.call_tool("get_token_info")
        print(f"Auth0 audience: {result['audience']}")

if __name__ == "__main__":
    asyncio.run(main())
```

When you run the client for the first time:
1. Your browser will open to Auth0's authorization page
2. After you authorize the app, you'll be redirected back
3. The client receives the token and can make authenticated requests

<Info>
The client caches tokens locally, so you won't need to re-authenticate for subsequent runs unless the token expires or you explicitly clear the cache.
</Info>

## Environment Variables

For production deployments, use environment variables instead of hardcoding credentials.

### Provider Selection

Setting this environment variable allows the Auth0 provider to be used automatically without explicitly instantiating it in code.

<Card>
<ParamField path="FASTMCP_SERVER_AUTH" default="Not set">
Set to `fastmcp.server.auth.providers.auth0.Auth0Provider` to use Auth0 authentication.
</ParamField>
</Card>

### Auth0-Specific Configuration

These environment variables provide default values for the Auth0 provider, whether it's instantiated manually or configured via `FASTMCP_SERVER_AUTH`.

<Card>
<ParamField path="FASTMCP_SERVER_AUTH_AUTH0_CONFIG_URL" required>
Your Auth0 Application Configuration URL (e.g., `https://.../.well-known/openid-configuration`)
</ParamField>

<ParamField path="FASTMCP_SERVER_AUTH_AUTH0_CLIENT_ID" required>
Your Auth0 Application Client ID (e.g., `tv2ObNgaZAWWhhycr7Bz1LU2mxlnsmsB`)
</ParamField>

<ParamField path="FASTMCP_SERVER_AUTH_AUTH0_CLIENT_SECRET" required>
Your Auth0 Application Client Secret (e.g., `vPYqbjemq...`)
</ParamField>

<ParamField path="FASTMCP_SERVER_AUTH_AUTH0_AUDIENCE" required>
Your Auth0 API Audience
</ParamField>

<ParamField path="FASTMCP_SERVER_AUTH_AUTH0_BASE_URL" required>
Public URL of your FastMCP server for OAuth callbacks
</ParamField>

<ParamField path="FASTMCP_SERVER_AUTH_AUTH0_REDIRECT_PATH" default="/auth/callback">
Redirect path configured in your Auth0 Application
</ParamField>

<ParamField path="FASTMCP_SERVER_AUTH_AUTH0_REQUIRED_SCOPES" default='["openid"]'>
Comma-, space-, or JSON-separated list of required AUth0 scopes (e.g., `openid email` or `["openid","email"]`)
</ParamField>
</Card>

Example `.env` file:
```bash
# Use the Auth0 provider
FASTMCP_SERVER_AUTH=fastmcp.server.auth.providers.auth0.Auth0Provider

# Auth0 configuration and credentials
FASTMCP_SERVER_AUTH_AUTH0_CONFIG_URL=https://.../.well-known/openid-configuration
FASTMCP_SERVER_AUTH_AUTH0_CLIENT_ID=tv2ObNgaZAWWhhycr7Bz1LU2mxlnsmsB
FASTMCP_SERVER_AUTH_AUTH0_CLIENT_SECRET=vPYqbjemq...
FASTMCP_SERVER_AUTH_AUTH0_AUDIENCE=https://...
FASTMCP_SERVER_AUTH_AUTH0_BASE_URL=https://your-server.com
FASTMCP_SERVER_AUTH_AUTH0_REQUIRED_SCOPES=openid,email
```

With environment variables set, your server code simplifies to:

```python server.py
from fastmcp import FastMCP

# Authentication is automatically configured from environment
mcp = FastMCP(name="Auth0 Secured App")

@mcp.tool
async def search_logs() -> list[str]:
    """Search the service logs."""
    # Your tool implementation here
    pass
```
