Method

How x402 tracker entries are verified

A list is only worth citing if you know what was checked. This page says what I check before an entry goes on the x402 adoption tracker, what each check proves, and what none of them prove.

Two kinds of entry

Sellers charge for their own endpoints over x402. They can be checked at source, because the protocol leaves evidence: a 402 response with a payment challenge, a payTo wallet, and settlement on a chain.

Platforms and facilitators ship x402 support for others. Their entries rest on the named source, usually the vendor's own documentation or announcement. Traffic through a platform is not something I can see from outside, and the entry says so rather than implying otherwise.

The three checks for a seller

  1. Is the challenge real? I call the endpoint without paying. A live seller answers HTTP 402 with a payment challenge (an x402 version 2 payment-required header, or the equivalent JSON body) naming the scheme, the networks, the amount and the payTo wallet. Where the seller publishes a manifest at /.well-known/x402, I read that too. This proves the seller is serving x402 today. It does not prove anyone pays.
  2. Does the wallet belong to them? Where the manifest carries an ownership message and signature, I recover the signer and compare it with the payTo wallet. Where there is no signature, the entry says so under "not checked".
  3. Is anyone paying? I read the settlement wallet's token transfers on the chain the seller names, and the seller's own settlement feed if it publishes one. The count is a floor: explorers hide transfers they flag, and the chain cannot tell a customer from the operator's own test wallet. Where payment settles through a prepaid deposit (for example Circle Gateway), the payTo wallet shows nothing per call, and the entry is marked volume not observable rather than guessed.

Every entry records the date it was checked, the methods used, and what could not be checked. The same fields are in the raw data at majormatters.co/x402.json under verification.

The words, fixed

Status is one of three: live (verified running in production), announced (a public commitment, nothing shipped) or reported (a secondary report, unconfirmed).

Volume, for sellers, is one of five: no customer volume (the seller's own feed or wallet shows none), small (settlements exist, in the tens or low hundreds, and are visible),not observable (settlement leaves no per-call trace that can be read), material (a named source puts a figure on it), or unknown. "Live" and "paid" are different claims and are never collapsed into one word.

The daily probe

Lists go stale quietly. Every seller with a probe endpoint is called once a day by Major Labs, an independent research studio, and the result (answered or not, the x402 version, the networks offered, whether the payTo wallet matches the one on record) is published as open data. The tracker shows the last date each seller answered. A seller that stops answering stays listed with that date and a failure count, so the record shows what happened rather than deleting it.

The badge

A listed entry can show a dated badge that reads from the tracker, so it cannot say more than the entry does. It carries the entry's status, its volume word and the date it was last checked. Replace the slug with your entry's slug (the badge link under each company name on the tracker).

<a href="https://majormatters.co/x402"><img src="https://majormatters.co/x402/badge/goldsky.svg" alt="Listed on the Major Matters x402 adoption tracker" height="28"></a>

Example badge for a listed entry

Corrections

If an entry is wrong, write to hello@majormatters.co with the source. Corrections are logged on the change page with the date, and the original wording is not silently replaced. Nobody pays to be listed, and no entry is removed on request while the facts stand.

Submit an entry · Back to the tracker

Charlie Major is a Product Development Manager at Mastercard. The views and opinions expressed in Major Matters are his own and do not represent those of Mastercard.