I have made this blog to add links and information of all oi contest(official contest/mirror) happening this year.I missed out the official contests of IZHO and infocup(didn't come to know and no blog post on cf as well).Please post a comment if you know any other OI contest with contest date/registeration date or link

JOI final round- https://contests.ioi-jp.org/joi-ho-2021/index-en.html
toki cms contest- https://codeforces.com/blog/entry/85545
Finnish Olympiad in Informatics- https://codeforces.com/blog/entry/87261
EGOI 2021 : https://egoi.ch/en/
infocup- https://www.info1cup.com/#schedule
COCI- https://hsin.hr/coci/
usaco- http://www.usaco.org/
APIO 2021- https://apio2021.id/
IOI 2021- https://ioi2021.sg/
Innopolis Open Olympiad in Informatics(finals on 21st February)- https://codeforces.com/blog/entry/84596 CEOI 2021- https://hsin.hr/ceoi/
IZHO 2021- https://izho.kz/izho-2021/about/
BOI(Baltic) 2021- https://bwinf.de/olympiade/boi2021/