United States of America Computing Olympiad (USACO)

International Olympiad in Informatics (IOI)

The IOI is the most prestigious computer science competition in the world for secondary school students. UNESCO and IFIP are patrons.

MatadorHacks

MatadorHacks is a hackathon for high school students in the Bay Area which will be held at Monta Vista High School on March 23-24, 2019.

Major League Hacking (MLH)

The official collegiate hackathon league.

HackGT

HackGT aims to promote computer science education in collegiate and high school communities. From organizing hackathons across disciplines.

Game Off

Ludum Dare

Global Game Jam (GGJ)

Codeforces

Codeforces. Programming competitions and contests, programming community.

Microsoft Imagine Cup

Imagine Cup is an annual competition sponsored and hosted by Microsoft Corp. which brings together student developers worldwide to help resolve toughest problem

Google Summer of Code (GSoC)

The Google Summer of Code, often abbreviated to GSoC, is a global program focused on bringing more student developers into open source software development.