Guides
Explainers that pull the reference pages together. Every factual claim links to a protocol entry, and each entry carries its primary sources and a verification date.
Agentic payments in 2026: the four layers, and which protocol does what
x402, AP2, A2A, MPP, Visa TAP, Mastercard AP4M, ACP, UCP — agentic payment protocols mapped to the four layers they actually occupy, with sources.
verified 2026-10-26