Crowdin - Localize your product in a seamless way
Anki - Anki is a program which makes remembering things easy. Because it's a lot more efficient than traditional study methods, you can either greatly decrease your time spent studying, or greatly increase the amount you learn.
POEditor - The translation and localization management platform that's easy to use *and* affordable!
Discovery FlashCards - Discovery FlashCards is a unique free program that can help you study.
Lokalise - Localization tool for software developers. Web-based collaborative multi-platform editor, API/CLI, numerous plugins, iOS and Android SDK.
RemNote - All-in-One Tool For Thinking & Learning