CF Focus — AI Blocker for Competitive Programming

About

CF Focus helps you train your problem-solving skills the old-fashioned way: by actually solving the problem.

The moment you open a competitive-programming practice tab, CF Focus quietly blocks AI chat assistants. When you close that tab, AI is reachable again. No toggles, no rituals, no willpower required.

The trick: there is a way out. But you have to earn it.

How it works

1. Open a coding-practice tab. The extension goes active and the toolbar badge turns red.
2. If you try to open an AI chat tool, you'll see a focus page instead, with a timeline showing how long you've been stuck on the current problem.
3. Stay focused. The longer you struggle, the more help you unlock — first a question-style hint about your approach, then a more specific algorithmic hint, then a button that grants you a short window of AI access. By the time you've earned it, you've already done the thinking that matters most.
4. Close the practice tab and everything returns to normal.

Every threshold (when each hint appears, how long an unlock lasts) is configurable in settings.

What you get

— Automatic on/off based on your tabs. No buttons to press.
— A focus page with a live "time invested" timeline.
— Earned-hint system that nudges before it answers.
— Optional timed Focus Sessions (15–90 minutes), including a Hardcore mode that genuinely cannot be paused.
— Schedule blocking on chosen days and hours, including overnight windows.
— A custom blocklist for any site that distracts you, and a custom platform list for practice sites we don't ship by default.
— Streak, daily-minutes goal, and "problems solved" counters.
— Optional PIN lock on the settings page, so future-you can't disable it on a whim.
— Keyboard shortcut to toggle snooze (Ctrl+Shift+B / Cmd+Shift+B).

Privacy

Everything stays on your device. There is no analytics, no telemetry, no third-party SDKs, and no remote server. Tab URLs are read locally to detect whether you're on a practice site; page content is never inspected. The PIN, if you set one, is stored as a SHA-256 hash. Full policy at the link below.

Who it's for

Anyone preparing for contests or interviews who has noticed that "quick AI lookups" have become a copy-paste habit. The struggle of being stuck is exactly where you grow — this extension just makes that struggle harder to short-circuit.

Open-source, no account required.