How it works
What happens after you submit a payment is on Atum payment lifecycle. How long the submit call waits, and what each status means, is on After submission. For a payment that is still settling, poll/status or re-submit the same request_id; over x402 or MPP, the payer re-attempts the same purchase. See When a payment is still settling.
Endpoints
New to the API? Build and sign a payment request with the SDK or CLI,
then submit it to /v1/payments. Full request and
response shapes are rendered from the spec on each endpoint page.
Request fields
You set every field of a payment request. The gateway never changes a field and never fills in a default; only the SDK and CLI fill in defaults, and only for values you leave out (see Prepare a payment). Your signature (sender_auth) authorizes the spend. It covers the source token, the most that may leave your wallet (max_source_amount), the recipient and the request_id. That is why max_source_amount is required on a payment and must equal the amount you signed. A quote request is not signed, so there it is optional.
No endpoint builds or signs a request. Build and sign it with the SDK or CLI, then submit it with the HTTP API.
Asset identifiers
Assets use CAIP-19 format —{chain_id}/{asset_namespace}:{asset_reference}. For example, Ethereum USDC is
eip155:1/erc20:0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48.