268 open-source tests you can run on your own domain for $0.0005 each — and the one I built so AI agents can find them
I run an x402 paid API catalog on Base (USDC) with 268 endpoints — every one priced at $0.0005–$0.005 per call . The catalog covers web security, DNS, HTTP, email auth, TLS, certificates, accessibility, sustainability, and a dozen adjacent surfaces. Each one is a real linter, real probe, real HTTP
What they cost: less than a coffeeshop dollar to test your entire prod stack.
# 1. Pick what to test WORKFLOW = [ ( " /api/x402-cost-quote ", " path=/api/extract " ), ( " /api/catalog-integrity-audit ", " url=https://yoursite.com " ), ( " /api/buyer-wallet-preflight ", " path=/api/extract " ), ] # 2. For each call, fetch → parse WWW-Authenticate → settle → retry 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 ()) Enter fullscreen mode Exit fullscreen mode 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.
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 "