Quick start
A few lines to a working agent payment.
Install payagent, drop in your API key, wrap your fetch. The first 402 challenge is paid and retried automatically, with your spend limits enforced before anything signs.
import { payFetchDelegated } from 'payagent';
const fetch402 = payFetchDelegated({
arispayUrl: 'https://api.arispay.app',
apiKey: process.env.ARISPAY_API_KEY,
});
// 402 challenge is paid automatically — spend limits enforced server-side.
const res = await fetch402('https://api.example.com/premium');Two SDKs. One platform.
For agent builders
PayAgent
Agent-side x402 SDK. Wrap any fetch call with payFetchDelegated() and pay HTTP 402 challenges automatically. Vercel AI SDK + LangChain adapters included.
For merchants
PayGate
Server-side middleware. Drop paygateExpress() or paygateFastify() on any route to gate it behind a price. Settlement runs on Base mainnet through our open hosted facilitator — USDC and EURC, no fee, no gas subsidy.
Built like you'd build it.
The boring stuff is done. Spend the time on the agent, not the payments plumbing.
Idempotent by default
Every POST takes an Idempotency-Key. Retry as much as your network does. We dedupe on the server.
HMAC-signed webhooks
Every webhook carries an HMAC-SHA256 signature plus replay-protected timestamp. Verify in one helper call.
Delegated custody
x402 signing runs through Coinbase CDP. The key never touches your servers. Spend caps enforced before the signature.
One Payment schema
Every rail responds with the same Payment shape — amounts in integer cents, always. x402 is live; card and channels roll out behind the same contract.
Mock + live providers
PAYMENT_PROVIDER=mock for tests, live x402 settlement for prod. Same SDK, same response shape.
Stable error codes
Errors are strings, not HTTP statuses. SPEND_LIMIT_EXCEEDED, X402_PAYMENT_FAILED, CARD_DECLINED. Switch on them.