x402 listing lint
Paste your 402 response and see which CDP Bazaar listing rules it passes, with a one-line fix for each that it does not.
Runs entirely in your browser
Input up to 1 MB of JSON. Nothing is sent anywhere, and the page never contacts your endpoint.
How to lint an x402 listing
- Get your endpoint's 402 response, for example with curl -s -i URL. Type the URL in the second box to get that command.
- Paste the JSON body (or the base64 PAYMENT-REQUIRED header value) into the first box.
- Read the list. Each rule is pass, warn or fail, and every warn and fail has a one-line fix.
The rules this checks
The Coinbase CDP x402 Bazaar lists paid endpoints for agents to discover. Listing quality decides whether an agent can pick your endpoint without guessing. This tool checks the pieces you control in the 402 response.
- Description must be present and at most 500 characters. CDP rejects longer ones at settle time.
- A "when to use" sentence is a curation rule. In our index of 37,275 Bazaar records, 99.1% lack one, 104 are over 500 characters and 92 are empty.
- Resource URL must be https. mimeType and outputSchema must be present.
- Each payment option needs a positive integer amount, a network, an asset and a payTo address.
The full list, with the free validate call and the featured-tier criteria, is in How to get an x402 endpoint listed and featured in the CDP Bazaar. For payer counts by endpoint, see what agents pay for over x402.
Questions
Is my JSON uploaded?
No. The rules run in your browser and nothing is sent or stored. The page also does not fetch your endpoint.
Why can't I just enter a URL and have it fetched?
To keep the privacy promise, this page is not allowed to contact other sites, and most paid APIs do not send CORS headers anyway, so a browser could not read the response. Enter the URL to get a curl command, run it, and paste the body.
Which formats are understood?
x402 v1 (description, mimeType, outputSchema and maxAmountRequired inside each accepts entry) and v2 (resource object, amount, and extensions.bazaar). A bare accepts entry and the base64 PAYMENT-REQUIRED header value also work.
Is this the official validator?
No. It checks the documented rules and the curation criteria we collected in the Bazaar listing checklist. For the authoritative result, call the free CDP validate endpoint described there.
How is the when-to-use sentence detected?
By phrases such as "use when", "use this to", "call when", "best for" and "ideal for". It is a warning, not a failure, because curation is editorial.