Interactive playground

The witr playground runs a simulated Linux box in your browser. Nothing is installed, nothing leaves your machine, and the scenarios behave the way a real box would.

It is the fastest way to decide whether witr belongs in your toolkit.

What you can do there#

• Guided tutorial — walks through a realistic failure: a deploy aborts with EADDRINUSE on port 8000, and you trace what is holding it.
• Free-play sandbox — a simulated Ubuntu 24.04 box with 22 processes to poke at however you like.
• TUI mode — the same four-tab dashboard you get from witr -i, rendered in the browser.
• Scenario reset — put the box back to a known state whenever you want to start over.

The scenario it opens with#

deploy@webbox:~$ ./deploy.sh
▸ building expense-manager … done
▸ health-checking :5000 … ok
▸ starting metrics endpoint on :8000 …
✗ Error: listen EADDRINUSE: address already in use 0.0.0.0:8000
  deploy aborted. something is already on that port.

This is the exact case witr was built for. lsof -i :8000 gives you a PID. witr gives you the chain that put it there, so you know whether killing it is safe.

The walkthrough for the same investigation on a real machine is in Query by Port.