Hey Codeforces!

CF Stopwatch — a tiny browser extension I built that auto-injects a stopwatch directly into Codeforces problem pages. No setup, no manual effort — it just works.

TL;DR

If you want to track how long you actually spend on a problem without leaving the page or starting/stopping a separate timer, CF Stopwatch does that for you automatically.

Why I built it

I kept losing track of how long I was spending on problems. Opening a separate timer, remembering to start/stop it, or finding out it had been running in another tab broke my focus. I wanted a timer that lives inside Codeforces itself and requires zero interaction.

What it does

Anti-panic buffer — A 60-second delay before the timer starts so you can read the problem and decide whether to attempt it (or manually start earlier). No clock-stress the moment the page opens.
Auto-stop on Accepted — The extension polls the Codeforces API every 5 seconds and freezes the timer as soon as your submission receives Accepted. (You must be logged in for this to work.)
Multi-attempt support — Hit Reattempt to reset the clock for a fresh try. Previous AC verdicts are ignored for the new attempt.
Smart persistence — The timer only runs while the tab is open. Close the tab and it freezes; reopen and it resumes exactly where it left off. Nothing runs silently in the background.
Adaptive theme — The widget reads colours from the Codeforces page at runtime so it blends with light/dark/custom themes automatically.