x402
Payments for AI agents, over plain HTTP.
x402 revives the HTTP 402 status so any API can quote a price in USDC. Furlpay serves real 402 challenges and verifies payment payloads today; on-chain settlement is in development.
x402 lets an AI agent request a resource, receive a 402 Payment Required response, pay in USDC, and retry — no API keys, no human checkout.
Where this stands today. The challenge and verification halves are live — a GET to /api/x402/fx returns a real 402 with an EIP-3009 accepts block you can integrate against right now. Settlement is in development: Furlpay's production facilitator signer is not configured, so /api/rails reports this rail as not configured and an agent cannot complete a payment through us yet.
Infrastructure for agentic commerce
HTTP 402, revived
x402 uses the long-reserved 402 Payment Required status so any API can quote a price and get paid inline.
Agent-native
An agent hits a resource, receives a price, pays in USDC, and retries — no API keys or human checkout in the loop.
Facilitator API
A facilitator that verifies payment payloads so resource servers never touch chain logic. Settling them on-chain is in development — production signing is not yet configured.
Micropayments
Sub-cent Arbitrum gas makes per-request pricing viable — charge fractions of a cent per call.
MCP-ready
Pairs with our MCP server so tools exposed to models can be metered and paid for automatically.
Open-source
The facilitator and middleware are MIT-licensed — self-host or use the hosted endpoint.
Frequently asked questions
What is the x402 payment protocol?
x402 is an open protocol that uses the HTTP 402 'Payment Required' status code to let a server quote a price for a resource and a client — often an AI agent — pay for it inline, typically in USDC stablecoin. It enables pay-per-request APIs without accounts or API keys.
How do AI agents pay with x402?
An agent requests a resource, receives a 402 response with payment details, submits a signed USDC payment, and retries the request. On Furlpay the challenge and verification steps run in production today — you can call /api/x402/fx and get a real 402 back. The final settlement step on Arbitrum is in development: the production facilitator signer is not configured, so an agent cannot yet complete a payment through us.
Why USDC on Arbitrum for agent payments?
Agent workloads make many small calls, so fees must be tiny. Arbitrum gas is a fraction of a cent and USDC is dollar-stable, which makes true per-request micropayments economically viable.
Is Furlpay's x402 facilitator open-source?
Yes. The facilitator and payment middleware are MIT-licensed on GitHub. You can self-host or call the hosted endpoint at /api/x402/facilitator.
Meter your API for agents
Open-source middleware and a facilitator you can self-host today.