your 404 page has a blind spot

Han Wang tweeted something last month that stopped me mid-scroll: 48% of all docs visitors across sites powered by Mintlify are from AI agents.

Half the traffic hitting your documentation isn't human. And your 404 page's cute illustrations, search bar, go back to homepage message, recommended links, etc... were built for humans.

When an AI agent hits a 404, it doesn't see any of that. It gets a blank wall. Then it either tells the user "I couldn't find that" or hallucinates something plausible.

So I built agent404.dev to solve this. Just add a one-line script tag on your site:

<script
  src="https://agent404.dev/agent-404.min.js"
  data-site-id="your-site-id"
  data-api-key="your-api-key"
  defer
></script>

It indexes your live pages in the background. When someone hits a 404, it matches the dead URL against your index and returns ranked suggestions — as both a human-readable list and schema.org JSON-LD that agents already understand.

The kinds of broken links it catches:

• Hallucinated URLs — agent invents auth0.com/docs/customize/login-pages/acul when the real path is /advanced-customizations
• Typos — docs.stripe.com/payment/checkout instead of /payments/checkout. One character. No redirect covers this.
• Docs restructures — Next.js moved static export docs from a deep nested path to /docs/app/guides/static-exports. Every old link is dead.
• Path renames — Vercel moved Edge Functions from /docs/edge-functions/overview to /docs/functions
• Subtree moves — Supabase shifted auth docs from /docs/auth/ to /docs/guides/auth
• Missing segments — agent links to react.dev/reference/hooks, dropping the /react/ segment

View more use-cases here- https://agent404.dev/demo

All the above 404 examples are silent failures or a hallucinations. But with Agent 404, the agent gets pointed to the right page.

Open source. MIT license. <3Kb script. Self-host on Vercel or Cloudflare Workers, or use the hosted version at agent404.dev.