What x402 is
x402 uses the existing HTTP 402 Payment Required status to let a server quote payment terms for a resource. A capable buyer can inspect the challenge, apply its own authorization and wallet rules, settle through a supported rail, and retry the request with proof of payment. It is a settlement pattern for machine calls, not a complete wallet policy or proof that the returned data is useful.
How an autonomous agent pays an API
A robust flow has separate stages: discover the resource and price; request it without assuming payment; validate the challenge, asset, network, recipient, amount, and retry URL; compare the purchase with the principal’s budget and policy; authorize and sign only if permitted; retry idempotently; then retain settlement and fulfillment evidence. Discovery is not authorization, and a stated budget is not consent.
The payment infrastructure landscape
The live Agent Payments & Commerce Index covers protocols, wallets, routers, marketplaces, identity systems, and monetization layers. x402 is one settlement rail among a broader stack that also includes authentication, delegated authority, commerce protocols, and buyer-side controls. Routing can compare rails, but the buyer still needs explicit limits, allowlists, replay protection, and a record of what was purchased.
Observed behavior versus declared support
Machine Observer keeps vendor claims separate from probes. The measured record illustrates why: one source tracked large cumulative x402 activity, while independent catalogs and route probes measured much smaller sets of discoverable, callable, or valid-challenge services. These denominators describe different populations. A declared x402 logo does not prove a valid challenge, and a valid quote does not prove paid fulfillment.
What the measured record says
Agent Economy tracked 176,520,376 x402 transactions and $41,547,691 in cumulative settled value as of its August 31 refresh.
Graded reported 3,906 discoverable x402 services, of which 3,078 were callable through its gateway at its latest published probe.
TOLL·402 confirmed valid x402 requirements on 19,259 of 77,809 quote-testable canonical routes in its August snapshot; the edition did not claim paid-call verification.
The Agentic Payments Landscape cataloged 33 entries across substrate, identity and trust, authorization, commerce and checkout, and settlement and rails.
Use the live data
This guide explains the concepts; the underlying index continues to change. Open the related live index and methodology →
Interpretation boundary
Counts and probes are reported with their own populations and timestamps. Vendor declarations remain distinct from direct observations; no individual measurement is presented as a total market size or universal trust verdict.
Read the Machine Observer methodology →
For machine readers
sector: machine-commerce
last_updated: 2026-09-03
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