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Codeforces
What it is
Codeforces is a programming-contest community and platform where participants solve problems and receive ratings that reflect their skills. The site says it organizes approximately six contests each month, with participation free and open to everybody. In contests that follow Codeforces rules, contestants earn points for solving problems quickly and can test other participants’ solutions through hacks. Ratings use a modified Elo system, and contestants are grouped into two divisions. The online judge checks solutions against prepared tests and tests suggested through hacks, then returns a verdict. Past contests are available for practice, and the site says learning content and training features are in development. Codeforces also provides an API that returns some data as machine-readable JSON through HTTP requests. Public data can be requested anonymously, while private user data requires an API key. The API allows at most one request every two seconds; faster requests receive a call-limit error. Supported languages include C, C++, C#, D, Delphi, F#, Free Pascal, Go, Haskell, Java, JavaScript, Kotlin, Node.js, OCaml, PascalABC.NET, Perl, PHP, PyPy, Python, Ruby, Rust, and Scala.
For and against
For
- Contest participation is free and open to everybody
- Approximately six contests are organized each month
- Past contests are available for practice
- Judge returns verdicts on submitted solutions
- Supports a wide range of programming languages
Against
- API requests are limited to one every two seconds
- Private user data requires an API key
- Learning content and training features are in development
The verdict
Codeforces combines regular contests, rated participation, and an online judge with past contests for practice. Its API has a strict request limit, and private user data requires an API key.
Who it suits
Codeforces suits programmers who want to participate in contests, practice with past problems, or use its API for public data. Contestants can use a range of supported programming languages.
Plans and prices
Codeforces
Contest participation is free and open to everybody
Read 29 Sep 2026 · codeforces.com
On the record
- Account rules
- The FAQ says users should not create more than one account and should use the password reminder system if they forget their password.codeforces.com · read 29 Sep 2026
- API
- The API provides some Codeforces data as machine-readable JSON through HTTP requests.codeforces.com · read 29 Sep 2026
- API access
- API methods can be requested anonymously for public data, while private user data requires an API key.codeforces.com · read 29 Sep 2026
- API limit
- The API allows at most one request every two seconds; faster requests receive a call-limit error.codeforces.com · read 29 Sep 2026
- Contest format
- In Codeforces-rule contests, participants solve problems, receive points for solving quickly, and can test other contestants’ solutions with hacks.codeforces.com · read 29 Sep 2026
- Contests
- The site says it organizes approximately six contests each month and that participation is free and open to everybody.codeforces.com · read 29 Sep 2026
- Online judge
- Solutions are tested on prepared tests or tests suggested through participant hacks, and the system returns verdicts.codeforces.com · read 29 Sep 2026
- Practice
- Past contests are available for preparation, and the site says it is developing learning content and training features.codeforces.com · read 29 Sep 2026
- Privacy and data
- The privacy policy lists cookies, usage data, location, email, names, date of birth, country, city, delivery address, password, and company name among data it may collect.codeforces.com · read 29 Sep 2026
- Security
- The privacy policy says the data controller takes appropriate security measures to prevent unauthorized access, disclosure, modification, or destruction of data.codeforces.com · read 29 Sep 2026
- Skill ratings
- Contest ratings use a modification of the Elo rating system, and contestants are grouped into two divisions.codeforces.com · read 29 Sep 2026
- What it is
- Codeforces is a programming-contest community and platform where contests are held regularly and ratings reflect participants’ skills.codeforces.com · read 29 Sep 2026
