Glossary
An open standard that uses the HTTP status code 402 (Payment Required) so that an API can ask for payment and clients, including agents, can pay and retry. It is maintained under the Linux Foundation.
seller
Section titled “seller”The owner of an API or service that charges for requests with x402. op8x builds its tools for sellers.
402 challenge
Section titled “402 challenge”The response an x402 server sends when a request has no valid payment. It states what the server accepts as payment, and a client reads it to decide whether and how to pay.