Associations and Clubs
Austrian Riichi Association
European Mahjong Association
Kasu: Club for Japanese Games in Vienna
Learning Materials
EMA Riichi Mahjong Rules
Yaku/Score Table
Daina Chiba’s Riichi Book – excellent Strategy Book
Beginners Guide to Online Mahjong on osamuko.com
Mahjong Wiki with a wealth of information
mahjong.guide – Website with strategy articles and links
List of japanese terms
Scoresheet – with distances on tsumo
Applications and Platforms
Riichi Mahjong Flashgame – perfect to start with.
Majsoul riichi-platform with nice graphics, tutorials, manga style characters and ranking system
Tenhou.net – One of the biggest online platforms for Riichi Mahjong
Translation Plugins are available for Chrome and Firefox.
Mattari Mahjong – a very strong Application for Windows to play against
Interface Translation of Mattari Mahjong
Tenhou Mobile App
Mobile App for Offline Play in Japanese
Mahjong Tricks – mobile app for practicing complex waits
Advanced Tools
https://mjai.ekyu.moe/
Social Media
RyanPin – Facebook Group
Mahjong News on Facebook
Mahjong on Reddit
Mahjong on Discord
Websites
Mahjong News – Mahjong News Website
mahjong-ny.com – Website of the New York Mahjong Club
Comparison of Riichi Rules
http://arcturus.su/ – A big Mahong Wiki and Tenhou Documentation
Japanese Mahjong Blog about Jansou Games