Our Discord: https://discord.gg/ajezQHdnRU. Please email mathteca@gmail.com if any organization or society wants to partner with Mathteca.
JPhO (in Japanese)
Moscow City Physics Olympiad (In Russian)
MIPT (Fiztekh) Physics Olympiad (In Russian)
Saint Petersburg Physics Olympiad (In Russian)
Belarusian Physics Olympiad (In Russian)
EstPhO (in Estonian)
Eötvös Competition (in Hungarian)