x402

x402 is an open payment protocol that uses the HTTP 402 Payment Required status code to enable machine-to-machine payments. HumanConnection supports x402, allowing AI agents to pay for API calls on-the-fly without pre-provisioned API keys.

Overview

With x402, your agent doesn’t need a HumanConnection account or API key upfront. Instead, it makes a request, receives a 402 response with a payment challenge, completes the payment (typically via a crypto wallet), and retries the request with a payment proof header.

This is ideal for autonomous agents that manage their own wallets and need to discover and pay for services dynamically.

How it works

Agent                          HumanConnection API
  |                                    |
  |-- POST /v1/humans/search -------->|
  |                                    |
  |<-- 402 Payment Required -----------|
  |    X-Payment: {"amount": 0.05,    |
  |     "currency": "USDC",           |
  |     "network": "base",            |
  |     "address": "0x..."}           |
  |                                    |
  |  [Agent completes payment]         |
  |                                    |
  |-- POST /v1/humans/search -------->|
  |    X-Payment-Proof: "0x..."       |
  |                                    |
  |<-- 200 OK -------------------------|
  |    [{ name, bio, profiles, ... }] |

Pricing per tool

Supported currencies and networks

When to use x402

Next steps