Codeforces
Codeforces is a programming-contest community where participants solve problems, earn ratings, and prepare with past contests. The platform says it organizes approximately six contests each month, with free participation open to everyone. In contests following Codeforces rules, contestants earn points for solving problems quickly and can test other contestants’ solutions through hacks. Ratings use a modified Elo system, and contestants are split into two divisions. The online judge checks submissions against prepared tests and tests proposed through hacks, then returns a verdict. Codeforces also provides an API that returns some public data as machine-readable JSON through HTTP requests. Public data can be requested anonymously; private user data requires an API key. The API limit is one request every two seconds, with faster calls returning a call-limit error. Past contests are available for practice, and the site says learning content and training features are in development. Codeforces is free and supports languages including C++, Java, Python, JavaScript, and Rust.
Who it is for
Codeforces suits programmers preparing for contests or building problem-solving skills through timed competitions and past problems. Its API may also suit developers who need public Codeforces data in JSON.
What is good
- Contest participation is free and open to everyone.
- Approximately six contests are held each month.
- Past contests are available for practice.
- Solutions receive verdicts from an online judge.
- Supports a broad range of programming languages.
What to know first
- API requests are limited to one every two seconds.
- Private user data requires an API key.
- Learning content and training features are still in development.
Verdict
Codeforces centers on competitive programming, with recurring contests, practice from past contests, and an online judge. Keep its API rate limit in mind if you plan to request data programmatically.
Codeforces plans and pricing
All plansCompared on coding challenge sites
- Free plan
- Yes
- Primary use
- contests
- Languages supported
- C, C++, C#, D, Delphi, F#, Free Pascal, Go, Haskell, Java, JavaScript, Kotlin, Node.js, OCaml, PascalABC.NET, Perl, PHP, PyPy, Python, Ruby, Rust, Scala
- Solution explanations
- Yes
- Custom challenges
- Yes
- Company assessments
- No
