What they cost: less than a coffeeshop dollar to test your entire prod stack.
WORKFLOW = [
("/api/x402-cost-quote", "path=/api/extract"),
("/api/catalog-integrity-audit", "url=https://yoursite.com"),
("/api/buyer-wallet-preflight", "path=/api/extract"),
]
for path, q in WORKFLOW:
r = fetch(f"https://host{path}?{q}")
if r.status == 402:
pay = build_eip3009(path, r.headers["X-PAYMENT"])
r = fetch(path, headers={"X-PAYMENT": b64(pay)})
print(path, r.status, r.json())
A 5-call audit of your domain costs 268 × $0.0005 = $0.134 (about 14 USDC cents). The full pipeline — endpoint picker, payment builder, error diagnoser, retry loop, JSON report — fits in 60 lines.
I built it because no single paid API service catalog existed with this breadth at sub-cent pricing for AI agents. The full inventory lives at the standard /.well-known/x402 discovery path. Every endpoint ships with an extensions.bazaar block describing its input/output schemas so any agent that fetches a 402 envelope can plan the next call without scraping sample bodies.
Some of the endpoints:
| Surface | What it does | Price |
|---|---|---|
| DNS | A/AAAA/MX/NS/TXT/CNAME/HTTPS/SRV/CAA/DS/DNSSEC/RPKI/AXFR/DANE-chain | $0.0005 |
| HTTP | method-policy, smuggling-evidence, hop-by-hop-strip, encoding-integrity, QPACK-fingerprint, HTTP/3 readiness, CORS-runtime-attack, cache-poisoning, rate-limit-headers | $0.0005 |
| TLS | cert-transparency monitoring, OCSP-stapling check, OCSP-must-staple, DANE/TLSA, MTA-STS policy validation, SVCB/HTTPSSVC parser | $0.0005 |
| DKIM/SPF/DMARC rollup, BIMI selector rotation, MTA-STS policy violation parser, DANE/TLSA | $0.0005 | |
| Content-security | CSP-deep, CSP-inline-fidelity, CSP-source-list extraction, CSP-violation-replay, WASM-CSP analyzer | $0.0005 |
| Performance + accessibility | Lighthouse-style performance, accessibility audit, carbon footprint, forms audit | $0.0005–$0.002 |
| Buyer-side tools | x402-cost-quote (price any cart in 1 call),catalog-integrity-audit (score any seller's defects),buyer-wallet-preflight (live x402 settlement test from ephemeral key) | $0.0005 |
The buyer-side tools are the most novel: instead of paying per-call hoping nothing breaks, an agent can now price its full cart in one call, audit the seller for defects in another, and simulate an end-to-end settle from a funding-less ephemeral key in a third — all before committing real USDC.
Because time-to-insight matters more than cents-per-call:
If you run an AI agent that ships anything to the public web, this catalog turns "