HTTP API · operational

402registry

Checks whether AI crawlers (GPTBot, ClaudeBot, PerplexityBot) can see a website without JavaScript; findings with fixes, $0.01 per check over x402, no account.

Fetches a website the way AI crawlers do (plain HTTP, no JavaScript) and reports what they actually see: every finding quotes the fetched response and comes with a fix for the site's stack. One check costs $0.01 over x402, no account and no API key; a catalog snapshot of all checked sites costs $0.005. Free: look up the last dated verdict of a site, or queue a site for a free check. Catalog: https://402registry.com/.well-known/x402 and https://402registry.com/openapi.json; MCP server (no key): https://402registry.com/mcp; guide: https://402registry.com/llms.txt.

endpoint: https://402registry.com
auth: none (x402 payment per request)
try it: tested example call
curl -i "https://402registry.com/buy/one?site=https://example.com" # 402 with PAYMENT-REQUIRED (x402 v2, eip155:8453, USDC); repeat with PAYMENT-SIGNATURE from any x402 client. Free lookup: curl "https://402registry.com/api/check?url=https://example.com"
capabilities: check-ai-crawler-visibility · audit-website · lookup-site-verdict · download-site-catalog · submit-site-for-check
tags: seo · ai-crawlers · website-audit · x402
pricing: $0.01 per check, catalog snapshot $0.005 (USDC on Base via x402); lookup free
i/o: query parameters → application/json
docs: https://402registry.com/docs
machine-readable: /api/public/registry/402registry-api

Follow this tool

Get an alert when 402registry goes down, comes back, or quietly changes shape (response schema or tool list). Free for up to 3 tools. Pro: 100 tools + webhooks for your agents.

Get a key in one call

No account, no card

100 calls/day anonymous · 1,000/day with this free key · 50,000/day on Agent Pro. The key is returned instantly in the response — send it as the x-api-key header on any /api/public/* request. The key also lets you follow up to 3 tools and get an alert when one goes down or quietly changes shape. Email is optional; add yours to receive alerts, then confirm them from your inbox.

tested example call

curl -s -X POST https://agentnexus.app/api/public/keys \
  -H 'content-type: application/json' \
  -d '{"agent":"my-agent","purpose":"tool discovery","email":"you@example.com"}'

Use it from your agent

Point any MCP-capable agent (Claude, Cursor, your own) at the no-auth endpoint — it can then find 402registry and every other listed interface on its own:

tested example call

claude mcp add --transport http agent-nexus https://agentnexus.app/api/public/mcp

Agents can discover 402registry through the Agent Nexus MCP server, /llms.txt or the discovery API.