Skip to main content
Connect Claude Code to any Key0-powered service in two steps: add the seller’s MCP server and set up a payment wallet.

​
What You Need

  • Claude Code installed
  • The seller’s URL (e.g. https://my-service.example.com)
  • A funded wallet with USDC on Base (testnet or mainnet)
For testnet, get free USDC from faucet.circle.com.

​
Step 1: Install Payments MCP

@coinbase/payments-mcp handles wallet signing and on-chain settlement. Install it with the interactive setup: 
npx @coinbase/payments-mcp
The installer walks you through:
  1. Select Claude Code as your MCP client
  2. Choose automatic or manual configuration
  3. Complete the wallet login flow
Once installed, files are saved to ~/.payments-mcp/ and the server is registered in your MCP config automatically.
See the Coinbase Payments MCP docs for detailed wallet setup and authentication.

​
Step 2: Add the Key0 Seller

Add the seller’s MCP server to your .mcp.json (project root) or use the CLI:
.mcp.json
{
  "mcpServers": {
    "my-service": {
      "type": "http",
      "url": "https://my-service.example.com/mcp"
    }
  }
}

​
Finding the MCP URL

If the seller has MCP enabled, the URL is their base URL + /mcp: 
https://my-service.example.com/mcp
Verify by checking the discovery endpoint: 
curl https://my-service.example.com/.well-known/mcp.json

​
How It Works

Once configured, just ask Claude to use the service. Claude handles the payment flow automatically: 
You: "Get me the latest satellite photo of Tokyo"
Claude will:
  1. Call discover_plans — see available plans and pricing
  2. Call request_access — get a payment challenge
  3. Use payments-mcp to sign and submit the USDC payment
  4. Receive an access token (JWT)
  5. Call the protected API with the token
All of this happens in a single conversation turn.

​
Try It Locally

1

Start a Key0 seller

cd examples/express-seller
bun install && bun run start
The server starts at http://localhost:3000 with MCP enabled.
2

Set up payments-mcp

npx @coinbase/payments-mcp
Follow the interactive setup and complete the wallet login.
3

Add the local seller

claude mcp add local-seller --transport http --url http://localhost:3000/mcp
4

Fund your wallet

Get Base Sepolia USDC from faucet.circle.com for your wallet address.
5

Use Claude Code

Open Claude Code in the same directory. Ask it to interact with the seller — it discovers the plans, pays, and accesses the API.