Update: CF Stopwatch is now on Firefox Add-ons!

original post

Quick but exciting update — CF Stopwatch is officially available on Firefox Add-ons!

If Firefox is your browser of choice, you can now install it directly and use it seamlessly during your Codeforces practice sessions — no workarounds, no friction.

Firefox Add-on: https://addons.mozilla.org/en-US/firefox/addon/cf-stopwatch/

Huge thanks for all the support on the original post — it genuinely motivated this release. If you run into any issues or have feature ideas, drop them in the comments. Every suggestion helps shape what comes next.

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.

Screenshots

Installation

Chrome / Chromium

1. Download and unzip cf-stopwatch-chrome
2. Go to chrome://extensions, enable Developer mode
3. Click Load unpacked → select the folder

Firefox

1. Download and unzip cf-stopwatch-firefox
2. Go to about:debugging → This Firefox → Load Temporary Add-on
3. Select manifest.json

Download From Here

GitHub: pratikrkcha/CF-Stopwatch

If you find it useful, a star on the repo would mean a lot. Feedback and suggestions welcome — drop them in the comments below!

— Pratik Rakhecha

I have been trying for months, I get close enough, but then somehow fail to reach the threshold. I am able to solve question but I can do them fast enough.