Arcus documentation
Arcus is an independent x402 facilitator for the Arc blockchain. It verifies and settles USDC payments for APIs and AI agents. No account, no API key, no custody.
https://facilitator.arcusnetwork.coWhat Arcus does
x402 turns the HTTP 402 status code into a payment protocol. A server answers a request with 402 and a price, the client signs a USDC authorization, retries, and gets the resource. A facilitator sits in the middle so servers never touch a private key or the chain.
Arcus is that facilitator for Arc. It exposes three endpoints: GET /supported, POST /verify and POST /settle. Settlement submits the payer's signed EIP-3009 transferWithAuthorization from a relayer wallet that only pays gas. USDC moves straight from payer to merchant and never passes through Arcus.
curl https://facilitator.arcusnetwork.co/supportedHow a payment flows
Payment is settled only after your handler returns successfully. A failed request is never charged.
client ── GET /api/fact ───────────────────────▶ your server
◀── 402 + PAYMENT-REQUIRED ──────────────
client ── GET /api/fact + PAYMENT-SIGNATURE ───▶ your server ── POST /verify ──▶ Arcus
handler runs
your server ── POST /settle ──▶ Arcus ──▶ Arc
◀── 200 + PAYMENT-RESPONSE ──────────────Why Arc
Arc is an EVM chain built around USDC. Gas is paid in USDC and the native token is also the ERC-20, so a single balance covers everything. Blocks confirm in well under a second, which makes per-request micropayments practical. Because settlement is gasless for both payer and merchant, an agent wallet only needs USDC and a signing key.