Insights · September 2026
State of x402 endpoints.
What changed, named: five sellers changed a price in a month, one by 67 percent overnight with no change to its listing. Then the wider picture for 22,124 paid API listings from the buyer's side: which rails they sell on, how many answer when asked, and how long a challenge takes.
What changed, named
Observed by 402Signal's own probes, comparing successive challenges from the same URL. Every host is treated the same way and the method is published; a seller cannot pay to be left out, and nothing a seller pays for changes these numbers.
| Host | URL | Before | After | Observed | Rail |
|---|---|---|---|---|---|
| api.kadec0.xyz | /v1/serp | $0.030 | $0.050 | 10 Sep 00:02 UTC | Base |
| api.agentstools.dev | /search | $0.001 | $0.003 | 10 Sep 00:02 UTC | Base |
| api.syraa.fun | /news | $0.005 | $0.010 | 3 Sep 02:21 UTC | Algorand |
| netintel.dev | /gas/price | $0.005 | $0.002 | 3 Sep 00:07 UTC | Base |
| api.xfuel.app | /v1/chat/completions | $0.010 | $0.002 | 2 Sep 21:58 UTC | Solana |
Three up (by 67 percent, by three times, and by two times within four hours of the previous observation), two down. No recipient change was observed in a live challenge; the sixth tracked change in the period was 402Signal's own listing, where the catalog claim and the live challenge differ, and is excluded. Two of the five (api.syraa.fun and api.xfuel.app) also carried a catalog listing that named a different network and recipient from the live challenge, which is the second thing a buyer planning from a catalog would not see.
The discovery feeds' own change events are kept only briefly in the catalog copy; the first edition of this report, cut from the 12 September copy, counted one recipient change and eight price changes in listings during the period. Those are feed claims, not observations.
The catalog
By discovery source: CDP 15,977, PayAI 7,722, GoPlausible 927. The shadow catalog began on 30 August 2026, so every listing counts as new in this first period. Almost every listing leaves the facilitator implicit, which is why a buyer cannot tell from the catalog alone who will settle a payment.
Networks by listing share
| Network | Listings | Share |
|---|---|---|
| Base | 19,893 | 44.8% |
| Solana | 6,846 | 15.4% |
| Polygon | 2,434 | 5.5% |
| Arbitrum One | 2,287 | 5.2% |
| Monad | 1,513 | 3.4% |
| World Chain | 1,159 | 2.6% |
| X Layer | 935 | 2.1% |
| Algorand MainNet | 925 | 2.1% |
| BNB Smart Chain | 911 | 2.1% |
| Algorand MainNet (short id) | 876 | 2.0% |
| XRP Ledger | 864 | 1.9% |
| HyperEVM | 859 | 1.9% |
Base and Solana together are 60% of listings. The next six networks are all EVM chains that share Base's payment scheme, and together they add another 20%. 402Signal observes offers on all of them since 13 September; the checking fee is paid on Base, Solana or Algorand.
Capabilities
| Capability | Listings |
|---|---|
| unknown | 14,292 |
| market.price | 2,237 |
| search.web | 1,368 |
| compute.inference | 1,013 |
| market.analysis | 877 |
| chain.balance | 510 |
| travel.weather | 423 |
| identity.auth | 402 |
| messaging.notify | 328 |
| storage.files | 231 |
Two thirds of listings do not describe what they do well enough for a rule-based classifier to place them. Market data, web search and inference are the largest named categories. The ten largest hosts hold 30% of all listings.
Liveness and terms
Payable (a complete supported offer) 92.7%; invocable (an input schema present) 90.6%. URLs always live in the period: 285; never live: 50; flapping: 14.
| Rail | Probes | Live | Latency p50 | Latency p95 |
|---|---|---|---|---|
| Base | 1,253 | 95.2% | 719 ms | 2,416 ms |
| Solana | 493 | 96.1% | 1,094 ms | 2,484 ms |
| Algorand | 436 | 84.9% | 1,195 ms | 2,721 ms |
| Unknown | 214 | 88.3% | 333 ms | 1,209 ms |
Why probes missed: no 402 envelope 134, probe timeout 17, reachable with HTTP 200 and no challenge 10, upstream 5xx 7, blocked private address 2. The dominant miss is a listed URL that no longer answers with an x402 challenge at all.
Hosts, named
The fifteen hosts with the most public probes in the period. Each has a page at /endpoints/<host> with the same numbers, an embeddable badge and a claim link.
| Host | Probes | URLs | Live | p50 | p95 |
|---|---|---|---|---|---|
| payai.agentstools.dev | 354 | 41 | 100.0% | 1,116 ms | 2,322 ms |
| agent402.tools | 279 | 35 | 98.6% | 197 ms | 1,988 ms |
| api.kadec0.xyz | 166 | 8 | 100.0% | 744 ms | 2,239 ms |
| api.syraa.fun | 138 | 8 | 100.0% | 1,436 ms | 2,568 ms |
| api.agentstools.dev | 105 | 9 | 100.0% | 616 ms | 2,081 ms |
| agenthub-production-8c75.up.railway.app | 94 | 11 | 67.0% | 525 ms | 1,763 ms |
| api.eckari.com | 69 | 1 | 100.0% | 1,357 ms | 2,797 ms |
| ai-data-marketplace-1042299154756.us-central1.run.app | 66 | 2 | 100.0% | 1,077 ms | 2,002 ms |
| netintel.dev | 57 | 8 | 100.0% | 180 ms | 1,685 ms |
| 402.com.tr | 54 | 6 | 100.0% | 859 ms | 2,637 ms |
| x402.ottoai.services | 52 | 5 | 100.0% | 805 ms | 2,081 ms |
| agriintellect.site | 45 | 2 | 100.0% | 2,213 ms | 4,237 ms |
| api.delx.ai | 38 | 5 | 100.0% | 1,440 ms | 2,377 ms |
| api.onesource.io | 31 | 2 | 100.0% | 84 ms | 301 ms |
| hash-hmac.underscoredone.com | 31 | 1 | 100.0% | 164 ms | 1,079 ms |
What this says
- Prices move, and not only up. Five sellers changed a price in a month; the largest jump was 67 percent overnight with no change to the listing. A buyer that plans from a catalog price and does not check the live challenge at payment time pays whatever the challenge says.
- Roughly one listed URL in seven that 402Signal was asked about did not answer with a valid challenge. A catalog listing is not a live offer.
- Latency to a challenge is measured in seconds at p95 on every rail; the fastest hosts answer in under 200 ms. Buyers that time out at one second will miss live sellers.
- Listing share, not chain count, should drive which networks a checker observes: Base, Solana, then the EVM chains.
Method
A listing is a resource advertised by a facilitator discovery feed. A probe is an unpaid HTTPS GET (with a narrowly justified empty POST fallback) from 402Signal to the listed URL; live means the seller answered with an x402 402 challenge; payable means the challenge carried a complete supported offer; invocable adds an input schema. Latency is round trip to the challenge from Fly.io in Ashburn. A price change or recipient change is observed when the amount or payTo in a live challenge differs from 402Signal's previous trusted observation of the same URL within the period; the before and after values come from the observation rows on either side of the change clock. A listed change is a discovery feed's claim for a URL changing (the catalog listing, at its claimed time); listed changes are reported separately and never counted as observed changes. This edition counts 6 observed price changes and 0 observed recipient changes; the one recipient change in the first edition was a listed change. Sponsored and lab traffic classes are 402Signal's own tests and are excluded from the public numbers. Hosts are named because they are public catalog listings; neutrality means publishing the method and treating every host the same, not hiding the data.
Operate a host in this report? Open its page under Endpoints, embed the badge, and use the claim link to be named as a reference seller. Buyers can run the same unpaid check on any listed endpoint at Try a sample check and subscribe to change alerts with an admission key.