What this is
x402.review is a publication about x402 services: the single HTTP endpoints that charge a stablecoin amount per call, with no account, no API key and no subscription. A service review takes one such endpoint and answers the questions a buyer actually holds. What does a call do? What does it cost, on which chain, in which token? What arrives once it is paid for, and how does an agent spend it without a person in the loop? Where does the service stop being the right tool? The site covers two domains under one method: the services themselves, and the ground beneath them — how x402 challenges and settles a request, how a custom agent is assembled, and how that agent carries money.
How we review
Every review begins with a request the endpoint will not answer. The unpaid call returns a 402 challenge, and the review decodes it: scheme, chain, asset, amount, pay-to address, timeout. The quoted amount is the price reported — measured at the moment of the request, never copied from a catalogue or a price list. Ceilings are reported against the max_tokens that produced them, because a per-call figure means nothing without the completion length it buys. Where an endpoint exists, behaviour is tested: what the response contains, what an unsupported parameter returns, how the amount moves as the work grows. Where no endpoint exists, the piece is a preview and says so, and the price is given as unset rather than estimated. Nothing here asserts a capability that was neither tested nor labelled as design.
What we publish
Three kinds of piece. Service reviews, one service each, with measured prices and a tested boundary. Foundations, on the protocol itself: what x402 is, how a request is challenged, quoted and settled. Agents, on custom agents and how they pay: how they are assembled, what float they need, and what each call spent.
Field Notes, the speculative series of July 2026 — twenty posts on applications that did not yet exist — remains online as an archive and as an idea bank. It is not current work, and it is not maintained as though it were.
Who we are
x402.review is written and edited by N.P. Vincent. The publication is connected to x402.press, which sells the services reviewed here. That connection is disclosed on every piece that touches a service, and the commercial interest is stated plainly rather than placed behind the word “independent”. Promotional in intent, honest in content: a review that lists only strengths is an advertisement, and an advertisement is not worth the time it takes to read.
The relationship to x402.press and the studio
x402.press sells services by the call and lists them at /services/ — nineteen services today, four of them selling. The studio assembles custom agents from those parts and works out the specifications the previews describe. This site does neither: it carries the evidence and the explanation. Price tables here are measured snapshots taken at a stated date; the service pages are the live source, and the figures there are the ones the handshake quotes. Where a piece argues for a purchase, the argument is the measurement, and the service page beside it is where the purchase is made.
- The catalogue: x402.press/services
- The studio: studio.x402.press/design
Corrections
If a figure here is wrong, we correct it and say what changed. A correction is not a rewrite: the original measurement stays visible beside the corrected one, and the method note carries the date each figure was taken. Send the piece and the discrepancy to admin@x402.review.
