Daily Coding is a free, open-source platform for daily coding challenges. Every day there is exactly one new challenge, the same for everyone, all year round. The idea is borrowed from Advent of Code: one problem a day builds a habit, a catalogue of thousands does not.

You solve the challenge in a Monaco editor in the browser and run it against automated test cases in an isolated sandbox. Eleven languages are supported: JavaScript, TypeScript, Python, PHP, Ruby, Java, Go, C++, C#, Rust and Swift. Today's challenge can be solved without an account; signing up adds streaks, XP, levels, badges, daily, weekly and monthly leaderboards, and access to everyone else's solutions once you have submitted your own.

Daily Coding is non-profit, has no ads and is released under the MIT license. Built and run by one person as a side project.

Technologies: Next.js 16, React 19, TypeScript, Tailwind CSS, PostgreSQL, Prisma, Auth.js, Vitest
Infrastructure: Vercel, Neon, Hetzner, Piston

Website: https://daily-coding.dev

Source code: https://github.com/ledo9315/daily-coding