///// Free tools
Agent 404 Tester
See what an agent gets on a page that doesn't exist: the status code and whether the body explains where to go.
agent-friendly-404PARTIAL
Run it now
From any terminal, with Node.js. Nothing to install on your server and no account.
This runs the readability pillar. The checks below are in the report.
Run it here
See a sample report from a real scan of example.com.