How to pay with x402
Plain-English walkthrough of HTTP 402 → USDC authorization on Base → facilitator verify/settle → receipt. Same money on MCP via _meta payment fields.
Phase 0: discovery only. Payments are not live yet. This page documents the intended flow for when the gateway comes online at
api.defifintechdirectory.com / mcp.defifintechdirectory.com.- You (or your agent) request a tool — HTTP
POST /tools/{id}or MCPtools/call. - The server answers Payment Required (HTTP 402) with price, Base network, USDC, and the receive wallet (
payTo). - Your wallet signs a USDC authorization (EIP-3009). You typically don’t pay gas for that step — the facilitator does.
- You retry with the signed proof (
PAYMENT-SIGNATUREheader, or MCP_meta["x402/payment"]). - The server verifies, runs the tool, settles on Base, and returns the result plus a payment receipt.
- No account, no Stripe, no API key for buyers.
Network details
- Network:
eip155:8453(Base mainnet) - Asset: USDC · Scheme:
exact - payTo:
0x96873Fb532C630aE88c5e8A5dF5ef430c92dfF32 - HTTP base:
https://api.defifintechdirectory.com - MCP:
https://mcp.defifintechdirectory.com/mcp