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.
# 1. Ask the endpoint what it costs (no payment, no wallet needed): curl -i -X POST 'https://goodsong.dev/verify/repo' # -> HTTP/1.1 402 Payment Required # the response carries the price, asset and pay-to address. # 2. Pay and retry with any x402 client: npx x402-fetch -X POST 'https://goodsong.dev/verify/repo'
Endpoint: https://goodsong.dev/verify/repo. Operated by goodsong.dev, not by Animica. Price and availability were correct at the last probe on 2026-09-02 and are set by the operator, who may change them.
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-looki…
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 …
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.de…
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 consisten…
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 …