Independent reviews of the x402 APIs behind agentic commerce. I give an AI agent a real wallet, buy things with it, and publish every receipt.
Written by Neil·nothing here is sponsored·new? start here·how we grade
I pay for these APIs with my own wallet and publish what happened. The volume this market gets quoted by is mostly wallets paying themselves, so I read the payments off the chain myself. I check whether the answer that comes back is actually right, against a source that cannot be the seller. And the verdict an agent gates on is backed by money that moved. Every weight and threshold behind that is published at how we grade. The sweep covers every USDC payment agents make on Base and Solana, every day. Free MCP server for your agent →
This headline counts USDC received at the seller wallets we track, on Base and Solana, over the last complete UTC day. Of it, $31,459 settled on Base and $116,125 on Solana (Solana is mostly Bitrefill and Laso). The /x402 dashboard sweeps Base only, so it shows roughly the Base portion; a rolling-24h window there also differs from a calendar day by a few percent. Every figure on this site carries its scope for exactly this reason.
27 studies. A rating grades one service. A study is what a whole category, or the chain itself, turned out to be doing once we paid to find out. Every one is measured: swept from Base and Solana, or paid for with a real wallet and checked against what was promised. None is an opinion.
Most new sellers never get a single customer, so I became one. I picked 12 that showed up since Sept 4, each a cent or two, and paid each once. Ten sold to me, for 5.1 cents total.
Read the full finding and receiptsI started tracking who pays, not just who gets paid. From Sept 11 to 17, 5,445 wallets paid an x402 seller on Base. 5,012 of them (92%) paid just one.
Read the full finding and receiptsGrading 750 new sellers, my harness flagged 20 as charging more than they advertised, most often listed at $0.015 with my client reporting $0.020. Twenty overcharges is a story. It is also an accusation against 20 named businesses, so before it went anywhere I did the thing this site is built on: I checked the chain.
Read the full finding and receiptsWe give every x402 seller a pre-payment verdict: CLEAR, HOLD, or ABORT. The obvious question is whether that verdict is any good. So I joined it against the settlement tape, the real USDC agents paid each seller over the last seven days, and looked at where the money actually went.
Read the full finding and receiptsThe market lists new sellers constantly, and most of them nobody has ever paid, which is the gap this site exists to fill. So I pulled everything that appeared in the last week, set the factory-spam aside (one host alone sprayed 335 endpoints), and bought the ones that looked genuinely new: a nautical chart oracle, a grant database, a UK company registry, a Hyperliquid whale tracker. One call each, every response archived, judged against the seller's own declared output.
Read the full finding and receiptsFor weeks I had been measuring the objective slice of x402, the feeds you can check against a primary source. It is the easy part, and it is a fraction of what is out there. So I stopped narrowing, pointed the wallet at the entire market, and bought whatever looked interesting, one call each. Sixty cents later, here is what an AI agent can actually purchase today, every line with a transaction hash behind it.
Read the full finding and receiptsx402 is usually sized by transaction count, because the counts are enormous and the dollars are not. On the repaired tape, 6,386,618 payments settled between 2026-08-04 and 2026-08-20. Only 229,144 of them, 3.6%, went to sellers whose money came from a spread of independent buyers. The other 96.4% went to sellers where one wallet supplied 90% or more of that day's dollars. By dollars the picture inverts: 72% of the money went to the broadly held sellers. Both numbers are on the live dashboard.
Read the full finding and receiptsEvery settlement figure on this site comes from sweeping USDC Transfer logs on Base. On 2026-08-21 I found the sweep had been holding a single RPC endpoint for an entire run and writing off any block range that endpoint refused to serve. I re-swept every day from 2026-08-04 to 2026-08-20 with failover across providers and recursive splitting of oversized ranges, and recorded a day only when zero ranges were left unserved. The repaired tape holds 6,386,618 payments where the old one held 1,508,017. Every number this site published from that tape was low, and the leaderboard has been corrected in place.
Read the full finding and receiptsFinancial Modeling Prep sells a professional real-time stock feed. I wanted to know whether the cheap x402 APIs reselling stock quotes actually match it, so I paid eight of them for Apple's live price at the same moment and graded each against FMP's number, $305.93. Seven came back at $305.92 or $305.93, matching to the cent. It is the same result as every other objective-truth category on this site: when the answer is a fact, nobody gets it wrong.
Read the full finding and receiptsAn AI agent can search the web, read a blockchain, and hit a free weather endpoint on its own. So why is so much of the x402 economy selling it exactly those things? I paid two web-search APIs a tenth of a cent each to look up "x402 payment protocol." Then I ran the identical search with my own free tool and got ten results and a written summary instead of five links, at no cost. That is not a gotcha, it is the shape of an entire category, and the week's measurements say so.
Read the full finding and receiptsWallet balance lookups are the most-paid category in the whole x402 market, 217 buyers and about $69,000 a day. So I read one address's USDC balance straight off Base, $30.464119 held by vitalik.eth, and paid twelve balance APIs to tell me the same number. Seven returned a USDC figure and every one was exact to the cent. That is the whole point, and the reason is worth sitting with.
Read the full finding and receiptsUnderneath the price feeds and the sanctions screens, the x402 economy has a soul, and it is a very strange one. So I gave my agent's wallet a budget and bought the twelve oddest things I could find, one call each. It cost four cents, eleven of the twelve delivered, and what came back is the best argument I have that this market is real: nobody builds a signed-absolution endpoint for a demo.
Read the full finding and receiptsSanctions screening is the one category with a clean, public answer key: the OFAC SDN list. So I took three addresses that are currently on it and two clean controls (one of them my own wallet) and paid three services that sell wallet screening to check each one. Nobody let a sanctioned wallet through, which is the good news. The interesting part is how differently the three behave once you actually pay and look, and none of that is visible from a free check.
Read the full finding and receiptsThere is no single true temperature either, so I did not grade these against another weather API. I read the official observation from the National Weather Service station in New York, 84 degrees at KNYC, and then paid 12 sellers a tenth of a cent each, overriding every one of their location inputs to the same city. Seven returned a temperature and all were within about two degrees of the station. The accuracy is not the story. The story is that most of these are not really different services.
Read the full finding and receiptsGas is the cleanest thing to check on this whole site, because the answer is not a vendor's opinion, it is a number the chain publishes in every block. So I read the base fee straight from Base's latest block, 0.005 gwei, and then paid 10 sellers a tenth of a cent each for the current gas price. Six returned a real blockchain gas price and all six sat right on the chain's base fee. The other four are the story, and one of them sells the price of natural gas.
Read the full finding and receiptsThere is no single true price for Bitcoin, so I did not grade these against another price API, which would just measure which vendors agree. I graded them against a primary reference: the median of Coinbase and Kraken spot at the same second, which happened to agree to three thousandths of a percent. Then I paid 15 sellers a fraction of a cent each for the current BTC/USD price. Eight returned a real spot price and every one landed within 0.12% of the exchange, most within 0.02%. The interesting part is the other seven, and what the word price turns out to mean.
Read the full finding and receiptsThe market brags about payment volume. So I read it directly: every USDC payment into the payTo wallets of the 60 highest-revenue services on Base, for a week, grouped by who sent it. 2,864 wallets sent 1,088,819 payments worth $202,065. That looks like a broad, busy market. It is not. 975,292 of those payments, 89.6% of the whole count, came from one wallet paying one service, roughly 1.6 payments every second for seven days. Take that single wallet out and the payment count drops nine-fold.
Read the full finding and receiptsEvery x402 seller ships a schema: send this input, get these fields back. That is a promise, and almost nobody checks whether it holds, because checking means paying. So I paid. I sent each endpoint the exact input its own listing advertises, then compared what came back, field by field, against the output the same listing promises. I ran 549 endpoints through it. 345 returned a clean enough response to judge; of those, 306 delivered everything they promised, 89 percent, and 39 fell short. The other 204 could not be judged at all, and that gap is a finding in itself. Before recording a single shortfall I called that endpoint a second time, so nothing here rests on one bad response.
Read the full finding and receiptsEvery settlement number this site has published was swept from Base, because Base is where most x402 tooling points and it is the easy chain to read. We flagged the gap in writing and even proved it by making a payment of our own that our tape never saw. This week we finally swept Solana too. It carried $75,952 in a single day against Base's $66,440, so the chain we were not looking at held 53% of the market. The leaderboard was not slightly off. It was showing a minority of the money.
Read the full finding and receiptsAlmost every x402 challenge quotes a single number. api.surplusintelligence.ai, which sells OpenAI-compatible inference and has taken $19,013 in seven days, itemises it instead. Its challenge reports an estimated cost of $0.003302 for a small gpt-4o-mini call, of which $0.003000 is a flat x402 facilitation fee. The inference is about three hundredths of a cent. The rail costs ten times the goods, and the seller says so in the response.
Read the full finding and receiptsCoinbase's Bazaar shows how many calls and how many distinct wallets each listed API got in the last 30 days. That number is how anyone tells a live service from a dead one, which makes it the thing a new seller most wants and least has. Somebody noticed the number is a payment, and a payment is a thing you can buy. mudko.com sells exactly that, openly, as a listing inside the directory it is gaming.
Read the full finding and receiptsblockrun.ai sells stock quotes and web search by the call. It takes more individual payments than any other service on the tape and almost all of them come from a single wallet. Starting 2026-08-09 someone began generating addresses that begin and end with the same characters as blockrun.ai's real payment address, then sending a speck of USDC from each one so it would land in that customer's transaction history. Truncated, all 89 counterfeits read 0xe9030…1abf. So does the real address. blockrun.ai did nothing wrong here; the attack is aimed at the wallet paying it.
Read the full finding and receiptsTwo hundred services in the registry now sell trust: reliability pre-flights, reputation scores, merchant screening, attested delivery. I have one counterparty I can prove charged twice and returned nothing, with the transactions on chain. So I paid six of them to look at it.
Read the full finding and receiptsThe registry looks stable. It held 14,668 resources on 4 August and 14,828 on 10 August, a gain of about one percent. Underneath that, 2,803 endpoints appeared and 2,643 disappeared. Almost none of it was the market growing, and most of it was a handful of people.
Read the full finding and receiptsNansen returned nothing when I asked who first funded my agent wallet. That answer is correct, and it points at something structural: an agent wallet can move real money for a week without ever touching the chain as a sender. I checked whether that is normal. It is.
Read the full finding and receiptsYesterday a rival grader failed BlockRun because it only read the response body. I wanted to know how big that mistake is, so I probed 220 origins and looked in all three places the spec allows. It is not an edge case. It is most of the market.
Read the full finding and receiptsOn 2026-08-07 BlockRun advertised six free chat models needing no wallet, and I asked all six the same thirty-six questions. Two turned out to be the same model wearing different names. Re-tested on 2026-08-28, that catalog no longer exists and the free pool will not answer at all, so this is published as an observation rather than a grade.
Read the full finding and receiptsThe full feed · Every rating · Top paid services · Delivery checks · Field notes