Analysis of information sources in references of the Wikipedia article "Codeforces" in English language version.
At the moment, the most active contest site is Codeforces, which organizes contests about weekly.
CodeForces questions are more similar to questions in competitive programming
Codeforces — a Russian competitive coding site with contestants from around the world
Codeforces — a Russian competitive coding site with contestants from around the world
Difference between HackerRank, LeetCode, Topcoder and Codeforces: "Topcoder and Codeforces is a website that's typically used when preparing for actual competitive programming contests"