Understand the web. Build it yourself.

Debugging trails

Works here. Fails there. Find out why.

Six lessons and three guided cases for the journey from local files to a published site.

Follow the evidence one step at a time. These original simulations do not connect to a target site or read anything from your computer.

Build your diagnostic toolkit

  1. Resolve paths on the deployed site
  2. Catch the capital letter
  3. Is it the upload or the cache?
  4. A missing page needs the right response
  5. Find blocked resources on HTTPS pages
  6. Read the browser’s evidence

No account, score tracking or saved progress. Reloading starts a new attempt.