HTTP Header Checker
Sends a request to a web address you provide and reports back everything the server said in response: the status code, all the response headers, how many times it got redirected, and how long the whole thing took.
Go to this service →Our latest check (2026-10-11)
- Answering
- Yes — valid x402 payment terms
- Time to answer
- 240 ms
- Price
- $0.010 per call
- Paying buyers, last 30 days
- 3 (directory's own records)
- Paid calls, last 30 days
- 4
- Category
- Unclassified
- Address
- https://http-header-checker.underscoredone.com/check
Accuracy
Accuracy scores are published once a seller has enough paid checks against an independent record (at least 7 scored answers over at least 7 days). Until then no score is shown, and a missing score is never a pass.
For agents
This page as JSON: /sellers/8fa4924f89e0.json. Paid lookup by address: GET /api/seller?resource=… ($0.001, x402).