x402 APIs · Updated 2026-10-18

How DartzDabz scores x402 APIs

DartzDabz checks every x402 endpoint it tracks once a day with an unpaid, never-signing probe called DartzDabzBot. It sends one plain request without payment headers, honors robots.txt, and scores the reply from 0 to 100: responsiveness, HTTPS, speed, a valid HTTP 402 payment challenge, complete payment fields, and self-description. 607 x402 endpoints tracked as of Oct 18, 2026: 561 scored, 46 opted out via robots.txt.

x402 APIs · Methodology · Monthly reports · JSON feed

How does the probe work?

Robots.txt first. For each host the probe fetches /robots.txt and skips any endpoint whose path is disallowed for DartzDabzBot or all user agents. Skipped endpoints show as opted out.
One unpaid request. It sends a plain GET with no payment headers. Only if the endpoint answers 404 or 405 does it retry once as POST with an empty JSON body ({}).
Read the challenge. If the reply is 402 Payment Required, it parses the x402 payment requirements from the body or the PAYMENT-REQUIRED header. It never builds, signs or sends a payment.
Score and store. The reply is scored (below) and kept with its status, latency and check time. Each endpoint keeps its last 30 daily scores.

What are the crawl limits?

User agent: DartzDabzBot/1.0 (+https://dartzdabz.com/about/)
At most 1 request every 2 seconds per host, 4 hosts at a time, 10-second timeout
Run once a day; an endpoint is re-probed when its last check is over 20 hours old
Endpoints come from public catalogs: Coinbase's x402 Bazaar and Circle's agent marketplace

How is the score computed?

Check	Points
Responds within 10 s	15
Served over HTTPS	10
Latency: under 500 ms 10, under 1.5 s 6, under 3 s 3	10
Returns HTTP 402 Payment Required	20
Parseable x402 payment requirements with an accepts list	15
Required fields: scheme, network, payTo and amount (pro rata)	15
A description of the resource	5
An output schema or MIME type	10
Total	100

Grades: A 90+, B 80–89, C 70–79, D 60–69, F below 60. An endpoint that does not answer within 10 seconds scores 0 (F). Each listing also shows the fixes that would raise its score, such as returning 402 to an unpaid request or adding an output schema.

How many endpoints does this cover?

607 x402 endpoints tracked as of Oct 18, 2026: 561 scored, 46 opted out via robots.txt. Tracked endpoints = scored + opted out. Earlier briefs that quoted 561 were counting scored endpoints only.

Can I reuse the x402 score data?

Yes. The data in x402-scores.json is licensed under CC BY 4.0: you may copy, share and adapt it, including commercially, as long as you credit DartzDabz with a link to https://dartzdabz.com/. Suggested attribution: x402 endpoint scores by DartzDabz (https://dartzdabz.com/), licensed under CC BY 4.0.

What are the limits of this score?

It is a single daily check, not continuous uptime monitoring.
Because the probe never pays, it cannot confirm that a paid call settles or that the data returned is correct.
A high score is not an endorsement or a security audit. Give agents a dedicated wallet with a spend cap.

What else do people ask?

Does the DartzDabz probe pay for x402 calls?

No. The probe never pays, never signs anything and never sends payment headers. It only reads the 402 payment challenge an endpoint returns to an unpaid request.

How do I opt my x402 endpoint out?

Disallow DartzDabzBot (or all user agents) for that path in your robots.txt. The probe checks robots.txt for each host before probing, and opted-out endpoints are listed as opted out with no score.

What do the grades mean?

A is a score of 90 or more, B 80 to 89, C 70 to 79, D 60 to 69 and F below 60. Scores are automated single-point checks, not endorsements or security audits.

How often are x402 endpoints checked?

Once a day, during the daily rebuild around 6 AM Eastern time. An endpoint is re-probed when its last check is more than 20 hours old.

Data: x402-scores.json (every endpoint's grade, latency and last check) · monthly reliability reports · about DartzDabz.