x402
Payments for AI agents, over plain HTTP.
x402 revives the HTTP 402 status so any API can quote a price and get paid in USDC. Furlpay's facilitator verifies and settles on Arbitrum — built for the agentic economy.
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. Furlpay's facilitator handles verification and settlement on Arbitrum.
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
Furlpay's facilitator verifies and settles payments so resource servers don't touch chain logic themselves.
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. Furlpay's facilitator verifies and settles the payment on Arbitrum, so the resource server gets paid without handling chain logic.
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 hosted facilitator.