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New in version: 2.14.0 This guide shows you how to secure your FastMCP server using Supabase Auth. This integration uses the Remote OAuth pattern, where Supabase handles user authentication and your FastMCP server validates the tokens.

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Configuration

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Prerequisites

Before you begin, you will need:
  1. A Supabase Account with a project
  2. Your FastMCP server’s URL (can be localhost for development, e.g., http://localhost:8000)

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Step 1: Get Supabase Project URL

In your Supabase Dashboard:
  1. Go to Project Settings
  2. Copy your Project URL (e.g., https://abc123.supabase.co)

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Step 2: FastMCP Configuration

Create your FastMCP server using the SupabaseProvider:
server.py
from fastmcp import FastMCP
from fastmcp.server.auth.providers.supabase import SupabaseProvider

# Configure Supabase Auth
auth = SupabaseProvider(
    project_url="https://abc123.supabase.co",
    base_url="http://localhost:8000"
)

mcp = FastMCP("Supabase Protected Server", auth=auth)

@mcp.tool
def protected_tool(message: str) -> str:
    """This tool requires authentication."""
    return f"Authenticated user says: {message}"

if __name__ == "__main__":
    mcp.run(transport="http", port=8000)

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Testing

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Running the Server

Start your FastMCP server with HTTP transport to enable OAuth flows: 
fastmcp run server.py --transport http --port 8000
Your server is now running and protected by Supabase authentication.

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Testing with a Client

Create a test client that authenticates with your Supabase-protected server:
client.py
from fastmcp import Client
import asyncio

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

        # Test the protected tool
        result = await client.call_tool("protected_tool", {"message": "Hello!"})
        print(result)

if __name__ == "__main__":
    asyncio.run(main())
When you run the client for the first time:
  1. Your browser will open to Supabase’s authorization page
  2. After you authorize, you’ll be redirected back
  3. The client receives the token and can make authenticated requests

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Environment Variables

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

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Provider Selection

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

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FASTMCP_SERVER_AUTH
default:"Not set"
Set to fastmcp.server.auth.providers.supabase.SupabaseProvider to use Supabase authentication.

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Supabase-Specific Configuration

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

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FASTMCP_SERVER_AUTH_SUPABASE_PROJECT_URL
required
Your Supabase project URL (e.g., https://abc123.supabase.co)
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FASTMCP_SERVER_AUTH_SUPABASE_BASE_URL
required
Public URL of your FastMCP server (e.g., https://your-server.com or http://localhost:8000 for development)
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FASTMCP_SERVER_AUTH_SUPABASE_REQUIRED_SCOPES
default:"[]"
Comma-, space-, or JSON-separated list of required OAuth scopes (e.g., openid email or ["openid", "email"])
Example .env file: 
# Use the Supabase provider
FASTMCP_SERVER_AUTH=fastmcp.server.auth.providers.supabase.SupabaseProvider

# Supabase configuration
FASTMCP_SERVER_AUTH_SUPABASE_PROJECT_URL=https://abc123.supabase.co
FASTMCP_SERVER_AUTH_SUPABASE_BASE_URL=https://your-server.com
FASTMCP_SERVER_AUTH_SUPABASE_REQUIRED_SCOPES=openid,email
With environment variables set, your server code simplifies to:
server.py
from fastmcp import FastMCP

# Authentication is automatically configured from environment
mcp = FastMCP(name="Supabase Protected Server")
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