Pay per call.
USDC. Done.
Two production payment rails on every endpoint. Your agent advertises a wallet, our server advertises a price, the protocol does the rest. No Stripe form, no signup wall, no API key rotation.
Pay-per-call. Wallet-native.
Two production-grade payment rails on every endpoint. No signup, no API key, no Stripe form. Your agent points an OpenAI SDK at our URL and pays in USDC per request. We advertise the price in the 402, verify the signed proof, then return the LLM response.
MPP
Tempo · chainId 4217Machine Payments Protocol by Tempo + Stripe. Server advertises price in WWW-Authenticate: Payment, client signs with mppx, retries. Sub-cent payments with fee sponsorship support.
- Spec
- RFC 7235 (HTTP Authorization)
- Asset
- USDC.e
- Finality
- ~500ms
Authorization: Payment <credential>
x402
Base · chainId 8453Coinbase x402 spec. Standard 402 → EIP-712 typed signature → retry. Compatible with @x402/core, viem, MetaMask, Coinbase Wallet, Phantom (EVM mode).
- Spec
- HTTP 402 Payment Required
- Asset
- USDC
- Finality
- ~2s
X-PAYMENT <credential>
Dual-rail by design. The 402 challenge advertises both — your client picks whichever wallet it holds. Prices stay in parity across rails so there is no arbitrage to manage.
Read the specFive steps. No state held.
Client requests
POST /v1/chat/completions with messages and budget. No auth header needed.
Server returns 402
WWW-Authenticate: Payment (MPP) and an x402 challenge body. Price is tier-based: SIMPLE $0.001 to PREMIUM $0.015. Council = 5x.
Client signs
mppx signs MPP credential. @arcrouter/sdk signs x402 EIP-712. Both run automatically.
Retry with credential
Same request with Authorization: Payment OR X-PAYMENT header. Router verifies, charges, then routes to the model.
Response + receipt
200 OK with the model output plus Payment-Receipt or X-PAYMENT-RESPONSE header. Cryptographic proof for reconciliation.
Ready to test?
Free tier needs no wallet. Paid rails take a Tempo or Base USDC balance — fund with $0.50 and you can run hundreds of requests.