goodsong.dev publishes 6 machine-payable endpoints over the x402 protocol, priced from $0.005 to $0.01 per call. Each was probed directly; the response code below is what it returned.
| Endpoint | Method | Price | Probe |
|---|---|---|---|
| /verify/case | POST | $0.01 | 402 |
| /verify/citation | POST | $0.005 | 402 |
| /verify/package | POST | $0.005 | 402 |
| /verify/repo | POST | $0.005 | 402 |
| /verify/seller | POST | $0.005 | 402 |
| /verify/url | POST | $0.005 | 402 |
Verify a legal case citation: does it exist, and does the given case name match the canonical record? Catches a fabricated case citation, including a real-looking citation number paired with an invent…
Verify a citation: does it exist, is it retracted, and do the given title/authors/year/journal match the canonical record? Checked against Crossref (retraction data included) with OpenAlex as a fallba…
Verify a package: does it exist, is it deprecated or yanked, and does it have known vulnerabilities? Checked against the npm/PyPI/crates.io registry plus OSV.dev advisories.
Verify a GitHub repo: does it exist, is it archived or disabled? Catches an agent recommending or depending on a repo that's been renamed, taken down, or abandoned. Checked against the GitHub REST API…
Verify an x402 seller before paying it: does it exist and respond with a well-formed 402 challenge, is its own declared input/output schema internally consistent, and is its payout address sanctioned?…
Verify a URL: does it resolve, what's the final status and redirect chain, is it archived on the Wayback Machine, and (optionally) does expected text appear on the page. Checked via direct fetch and t…