CMC

The Cyberspace Mathematical Competition is a free, fun, high-level online invitational international contest for high school students, with teams of up to 8 people from each participating country. The competition consists of 8 essay-proof problems over 2 exams, each with a 5-hour time limit.

The CMC was run for the first time in 2020, and was inspired by the IMO being delayed.

View more details here: https://artofproblemsolving.com/contests/cmc