AlgoRadar Extension

Chrome extension to track upcoming competitive programming contests from multiple platforms.

Feature

• Multi-Platform: Codeforces, AtCoder, LeetCode, CodeChef, Kaggle, and more
• Smart Filters: Filter by platform and time (Today, Week, Month)
• Fast & Reliable: Contest data is served from scheduled, cached JSON updates with automatic background refresh
• Beautiful: Clean dark theme interface
• Secure: Backend API aggregates and caches CLIST data without exposing credentials
• Free Forever: No ads, no tracking, open source

Installation

From Chrome Web Store

AlgoRadar

Manual Installation (For Development)

1. Clone this repository
2. Open Chrome → chrome://extensions/
3. Enable "Developer mode"
4. Click "Load unpacked"
5. Select the extension folder

Project Structure

algoradar/
├── api/                      # Backend (Vercel serverless)
│   └── contests.js           # Serves pre-generated contest data (no runtime CLIST calls)
│
├── data/                     # Generated contest data
│   └── contests.json         # Cached JSON updated via local scheduled script
│
├── extension/                # Chrome extension
│   ├── manifest.json         # Extension manifest (MV3)
│   ├── background.js         # Background service worker (fetch + cache logic)
│   ├── popup.html            # Extension popup UI
│   ├── popup.css             # Popup styles
│   └── popup.js              # Popup interaction logic
│
├── .github/
│   └── workflows/
│       └── update-contests.yml  # Cron job to fetch contests from CLIST
│
└── README.md

Development Backend Development bash# Install dependencies npm install -g vercel

Run locally

vercel dev

Deploy to production

vercel --prod

Extension Development

1. Make changes in extension/ folder
2. Go to chrome://extensions/
3. Click reload icon on AlgoRadar
4. Test changes

Backend API (Data Service)

The backend is deployed on Vercel and serves pre-generated static contest data.

• Contest data is fetched via a scheduled GitHub Actions cron job
• Data is stored as static JSON and served to clients
• No runtime calls to CLIST API
• Eliminates rate-limit risks and cold-start issues
• Backend only reads cached data at request time

Data Update Architecture

Previous Approach(Deprecated)

• GitHub Actions cron job fetched from CLIST API
• Worked for 1700+ commits
• Issue: Cloudflare bot protection started blocking GitHub Actions IPs (403 errors)

Current Approach

• Local macOS script runs every 3 hours + on system wake
• Uses residential IP (trusted by Cloudflare)
• Commits and pushes to GitHub automatically
• Vercel detects push and serves updated data
• Zero Cloudflare blocks

Tech Stack

• Frontend: Vanilla JavaScript, HTML, CSS
• Backend: Vercel Serverless Functions
• Data Pipeline: Local scheduling script->GitHub->Vercel
• API: CLIST API
• Deployment: Vercel (backend), Chrome Web Store (extension)

Documentation

• Architecture and design rationale:
  https://github.com/nilanshucodes/algoradar/wiki/Architecture-and-Design-Rationale
• Also Checkout: Wiki

Contributing

Contributions welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Submit a pull request

Known Limitations

• Contest data updates when maintainer's machine is online (typically every 3-6 hours)
• If machine is offline for extended periods, data may be slightly stale (contests are announced days/weeks ahead, so this rarely affects users)
• UI remains intentionally minimal to keep the extension lightweight

Future Improvements

• Migrate to a 24/7 VPS for always-on updates (Oracle Cloud Free Tier or similar)
• Optional persistent storage (only if future scale requires it)

Latest Release (v1.2.0)

• Global Timezone: automatically detects your computer's system timezone.
• The "Time Remaining" now accurately matches the actual start time.
• Contests now remain visible and accessible right up until their official start time.
• No UI changes

License

GPL-3.0 License - see LICENSE

Attribution

• Contest data powered by CLIST
• AlgoRadar is an independent community project

Contact

• Issues: GitHub Issues
• Contact: Website

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Built with ❤️ for the competitive programming community