402registry

Agent-nativeFreemium

Site-audit agents can retrieve cached verdicts through REST or MCP, then pay over x402 in USDC on Base for a fresh check or enriched registry snapshot. The service uses its own plain-HTTP probes with four AI crawler user-agent strings, making it useful for diagnosing content delivery and firewall differences, not observing real crawler visits or predicting rankings.

Probes a website the way AI crawlers fetch it, sending GPTBot, ClaudeBot and other crawler user-agents, and keeps a registry of dated verdicts.

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Overview

About 402registry

402registry probes a website the way AI crawlers fetch it (plain HTTP, no JavaScript) and sends the user-agent strings of GPTBot, ClaudeBot, PerplexityBot and OAI-SearchBot to see whether the site, or a firewall in front of it, treats those requests differently. These are 402registry’s own probes, not the crawlers’ real visits, and a pass does not guarantee indexing, ranking or citation. Looking up the last verdict is free; running a fresh check or downloading the enriched catalog snapshot is paid over x402 in USDC on Base.

So agents can…

Look up the last dated verdict for a site with a free REST call or the remote MCP server (lookup_site, get_pricing, get_docs, get_service_status).
Pay $0.10 over x402 to run one check now, limited to 3 checks per hour and 10 per day for a site.
Pay $0.05 over x402 for an enriched catalog snapshot as one JSON file, or read the free basic registry.json.

Listing decision

Why 402registry is listed

Gives an agent or its builder a documented way to test whether a site serves its content to requests carrying the main AI crawlers’ user-agent strings, as a dated, public verdict that can be read as JSON.

Before you choose

Fit and limitations

Best for

Agents and site owners that need a dated, machine-readable answer on whether a website serves the plain-HTTP requests that GPTBot, ClaudeBot, PerplexityBot and OAI-SearchBot make, and whether a firewall treats those user-agents differently.

Not best for

General SEO analysis such as rankings or keywords, logs of real crawler visits, or checks of crawlers other than the four named ones.

Known limitations

Verdicts come from 402registry’s own plain-HTTP probes from Cloudflare that send the four crawlers’ user-agent strings (crawler page); they are not observations of the companies’ actual crawler visits, and a passing check does not guarantee indexing, ranking or citation (trust page). Free: cached lookups of a site checked before and the basic registry as registry.json. Paid over x402 in USDC on Base mainnet: a fresh check ($0.10 each, at most 3 per hour and 10 per day for a site) and an enriched catalog snapshot ($0.05 each). The public registry lists only sites that passed, not every private or failed report.

Not yet verified

No independent end-to-end paid check or accuracy benchmark was performed for this submission.

Sources

Sources and verification

First-party unless marked otherwise. Each link supports only its adjacent claim.

402registry agent guide (llms.txt)
Documents the free lookup and registry.json, the paid check and catalog snapshot endpoints with prices and limits, and the MCP tools.
official documentation · accessed Oct 12, 2026
402registry OpenAPI description
Describes the free check endpoint and the paid buy endpoints.
official specification · accessed Oct 12, 2026
402registry x402 discovery manifest
Lists the two paid resources for x402 discovery and points to the OpenAPI and service manifest for packs and prices.
official specification · accessed Oct 12, 2026
402registry paid check endpoint (unsigned 402 response)
An unsigned GET answers HTTP 402 with x402 version 2 requirements in the PAYMENT-REQUIRED header: scheme exact, USDC on Base mainnet (eip155:8453), 100000 units ($0.10).
official specification · accessed Oct 12, 2026
402registry crawler page
Lists the probe requests: plain HTTP from 402registry, including the same page fetched with the OAI-SearchBot, PerplexityBot, GPTBot and ClaudeBot user-agent strings; the requests come from 402registry, not from those companies.
official documentation · accessed Oct 12, 2026
402registry trust and verification page
Explains what one check measures and states that a passing check does not guarantee ranking, indexing, citation or inclusion.
official product page · accessed Oct 12, 2026
402registry public registry
Shows the public registry of dated verdicts for sites that passed, also available as JSON at /registry.json.
official product page · accessed Oct 12, 2026