Protocol / standardPublic reference
x402
Internet-native payment standard
A standard for requesting payment and supplying payment proof when accessing a digital resource.
THE QUESTION IT ADDRESSES
How can an agent pay for a resource inside a request?
A concise reading of published information. The explanatory grouping below is editorial, not an implementation test.
A simplified mechanism
- The service returns payment requirements.
- The client constructs a payment payload.
- The service verifies and settles, directly or through a facilitator.
What it does not establish
Client budgets and session management are outside the core specification. Fulfillment order depends on the payment scheme.
Where it fits
A wallet supplies signing capability. AP2 can supply authorization evidence; the official AP2 samples include x402 flows.
Sources & further reading
Sources reviewed on2026-10-26. Summaries are paraphrased; follow the current source for changes.