Top 5 contest-platform open source projects

JAlgoArena programming contest platform

ICTトラブルシューティングコンテストのスコアサーバー

Tadoku is a friendly foreign-language reading contest aimed at building a habit of reading in your non-native languages.

software for SamurAI Coding 2017-18

360Constest is an open source online platform that is capable to run contest marketplace sites aka 99designs clones designcrowd, zenlayout, logobids, etc. Supports image (logo, webdesign, etc), video (creative, etc), audio (voice-over, etc), text (content writing, blog, etc) contests