Hey fellow coders,

I made a Chrome extension called CF Themer.

Install: https://chromewebstore.google.com/detail/fogjbemaajokjgplblhlibebfjpbdjfd

Why I made it: I spend a lot of time on Codeforces, and three things kept bothering me:

1) The white site is hard on the eyes during late-night practice. 2) I wanted a timer and a place for notes on each problem without leaving the page. 3) Building a good practice set by hand takes ages, and the problemset filters don't give you a contest.

What's in it: - Themes: Monokai, Dracula, Pure Black and Lock-In. Switch with the popup, the ◐ button, or Alt+Shift+T. - Focus mode (Alt+Shift+F): shows only the problem statement. - Timer and notes: one per problem, saved in your browser. - Spoiler-free mode: hide tags, difficulty and solved counts. - Mashup contests: pick tags, rating range, number of problems and length. It builds a contest, runs a countdown across Codeforces, hides tags and ratings until it ends, then scores you with ICPC penalty. - Share codes: every mashup gets a short code, so a friend can get the exact same problems.

Privacy: No servers, accounts, analytics or ads, and I never receive your data. Everything stays in your browser. The only network requests go to the public Codeforces API, and the mashup builder asks for your agreement before it reads your handle or submissions.

Works on Chrome, Edge and Brave (version 111+).

Feedback: If a page looks wrong in your theme, tell me which page, and the element's class name if you can. I'd also like to hear which themes you'd want and what would make custom contests better for you. A rating on the store page helps others find it.

Good luck in your next contest!