OpenX402

Introduction

OpenX402 — the first permissionless x402 facilitator for AI agents

What is OpenX402?

OpenX402 is the first permissionless x402 facilitator. Any x402 server can use it to accept USDC payments — no sign up, no login, no API keys. Just point your middleware at facilitator.openx402.ai and start charging.

Built for AI agents and autonomous software that need to pay for API access without human intervention. An agent with a wallet can discover a service, read the price from a 402 response, sign a payment, and access the resource — all programmatically.

The x402 Protocol

The x402 protocol brings native payments to HTTP using the 402 Payment Required status code.

The flow:

  1. A client requests a protected resource from a server
  2. The server responds with 402 Payment Required and includes payment requirements (price, network, asset, recipient)
  3. The client signs a payment authorization (EIP-3009 on EVM, SPL TransferChecked on Solana)
  4. The client resends the request with the signed payment in headers
  5. The server forwards the payment to the facilitator for verification
  6. The facilitator verifies the signature and settles the payment on-chain
  7. The server returns the protected resource

The facilitator is the piece that verifies payment signatures and executes settlement on-chain. OpenX402 is that facilitator — permissionless, free, and live.

Why OpenX402?

  • No sign up — no accounts, no API keys, no KYC
  • Permissionless — any server can use it, any agent can pay through it
  • Free — no fees on verification or settlement
  • Multi-chain — Base, Monad, Solana mainnet, and Base Sepolia testnet
  • x402 v2 — full support for CAIP-2 network identifiers, discovery extension, and v1 backward compatibility

PayTo Whitelisting

PayTo addresses (the wallets that receive payments) can register via the Open token for whitelisting. This enables discovery and ensures your address is recognized across the facilitator network.

Next Steps

Quick Start

Start accepting x402 payments with the OpenX402 facilitator

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What is OpenX402?The x402 ProtocolWhy OpenX402?PayTo WhitelistingNext Steps