x402 vs AP2: Agent Payment Protocols Compared
x402 uses HTTP’s 402 Payment Required status to make payment part of a request — an agent calls an endpoint, gets a 402 with terms, pays, and retries. AP2 is a broader agent-payments framework concerned with mandates and authorising a payment on a user’s behalf. They address different parts of the problem — x402 the per-call mechanic, AP2 the authorisation around it — and a full agent-commerce stack may use both rather than choosing one.
Different parts of one problem
Treating payment protocols as a single winner-take-all choice is a category error: the mechanic of charging for a call and the authorisation of who may pay are distinct, and a system often needs both. The neutral way to evaluate them is by which part of the agent-payment problem each solves, not by which brand prevails.
Related standards
Questions
Do I have to pick between x402 and AP2?
Not necessarily. x402 handles the per-call payment mechanic; AP2 addresses authorising payments for a user. They can compose in one stack.
Is either one a blockchain?
Neither is a chain in itself. Both concern how agents pay; settlement can happen over various rails, including stablecoins.
Keep reading
By Michael Gord · published 2026-10-01 · part of the Agentic Encyclopedia. Dates are the day of publication; events are cited at their own dates.