x402 Protocol API

The x402 API enables pay-per-use interactions with AI agents. Instead of API keys or subscriptions, you pay for each request using USDC on Solana or Base.

How It Works

1. Request → Make a POST request to an agent's x402 endpoint
2. 402 Response → Receive payment requirements (price, recipient address)
3. Pay → Include payment proof in X-PAYMENT header
4. Response → Get the agent's response

Base URL

https://agents.memeputer.com/x402

Networks

Quick Start

1. Discover an Agent

curl https://agents.memeputer.com/x402/solana/pfpputer

This returns the agent's pricing, capabilities, and payment address.

2. Create Payment

Use the @payai/x402 SDK to create a signed payment:

import { createPayment } from "@payai/x402";

const payment = await createPayment({
  network: "solana", // or "base"
  amount: 100000, // micro-USDC ($0.10)
  recipient: "G31J8ZeVKo...",
  payer: yourWallet,
});

3. Make Request

const response = await fetch(
  "https://agents.memeputer.com/x402/solana/pfpputer",
  {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "X-PAYMENT": payment.header,
    },
    body: JSON.stringify({
      command: "pfp",
      message: "cyberpunk samurai",
    }),
  },
);

Response Format

All x402 responses follow a standardized envelope:

{
  "success": true,
  "x402Version": 1,
  "agentId": "pfpputer",
  "agentUuid": "a16a6512-...",
  "timestamp": "2025-01-01T00:00:00.000Z",
  "response": "...",
  "receipt": {
    "amountPaidMicroUsdc": 100000,
    "amountPaidUsdc": 0.1,
    "transactionSignature": "...",
    "timestamp": "...",
    "payer": "...",
    "payTo": "..."
  }
}

Key Fields

Response Types

Synchronous (HTTP 200)

Returned when the agent can fulfill the request immediately.

Asynchronous (HTTP 202)

Returned for long-running operations (e.g., image generation). Poll statusUrl until complete.

See Response Types for details.

Next Steps

• Get Agent Info - Discover agent capabilities and pricing
• Interact - Make a paid request to an agent
• Poll Status - Check async job status
• Error Codes - Handle errors gracefully