Codeforces (, sometimes written as CF) is a website (founded 2009) that hosts competitive programming contests. It is maintained by a group of competitive programmers from ITMO University led by Mikhail Mirzayanov. Since 2013, Codeforces claims to surpass site TopCoder (founded 2001, which also has a significant competitive programming component) in terms of active contestants. Codeforces along with other similar websites are used by some sport programmers, like Gennady Korotkevich, Petr Mitrichev, Benjamin Qi and Makoto Soejima, and by other programmers interested in furthering their careers.
Overview
Codeforces is a platform where people generally practice competitive programming and it offers the following features:
Short (2-hours) contests, called "Codeforces Rounds", held about once a week Educational contests (2-2.5 hours, with 12 hours (24 hours before Round 45) hacking period), held 2-3 times per month; Challenge/hack other contestants' solutions; Solve problems from previous contests for training purposes; "Polygon" feature for creating and testing problems; Social networking through internal public blogs.
Rating system Contestants are rated by a system similar to Elo rating system. There are usually no prizes for winners, though several times a year special contests are held, in which top-performing contestants receive T-shirts. Some bigger contests are hosted on Codeforces base, among them "The Lyft Level 5 Challenge 2018", provided by Lyft or "Microsoft Q# Coding Contest — Summer 2018" provided by Microsoft.
Contestants are divided into ranks based on their ratings. Since May 2018, users with ratings between 1900 and 2099 can be rated in both Div. 1 and Div. 2 contests. At the same time, Div. 3 was created for users rated below 1600. There is also a Div. 4, which is for users rated below 1400.
Rating rangeTitleDivision≥ 4000 13000 — 3999 12600 — 2999 12400 — 2599 12300 — 2399 12100 — 2299 11900 — 2099 1/21600 — 1899 21400 — 1599 2/31200 — 1399 2/3/4≤ 1199 2/3/4 During the period of time when the user tourist (Gennady Korotkevich) had a rating of >4000, he was given the title "tourist"; likewise, during the time when the user jiangly (Lingyu Jiang) had a rating of >4000, he was given the title "jiangly".
History Codeforces was created by a group of competitive programmers from Saratov State University led by Mike Mirzayanov. It was originally created for those interested in solving tasks and taking part in competitions. The first Codeforces Round was held on February 19, 2010 with 175 participants. As of the end of November 2025, over 1000 rounds were held, with over 11000 registered competitors per round on average. Before 2012, Codeforces Rounds were titled "Codeforces Beta Rounds" to indicate that the system was still under development.
Academic use Codeforces is recommended by many universities. According to Daniel Sleator, professor of Computer Science at Carnegie Mellon University, competitive programming is valuable in computer science education, because competitors learn to adapt classic algorithms to new problems, thereby improving their understanding of algorithmic concepts. He has used Codeforces problems in his class, 15-295: Competition Programming and Problem Solving. At the National University of Singapore, Codeforces rating is also used as an entrance qualifying criterion for registering for a 4-unit course, CS3233 Competitive Programming, as students have to achieve a rating of at least 1559 to be able to register for the course.
See also CodeChef CodeFights Competitive programming Facebook Hacker Cup Google Code Jam HackerRank International Collegiate Programming Contest :ja:AtCoder LeetCode Online judge SPOJ Topcoder UVa Online Judge
References
External sources Official website