Opal

Insight Timer is a meditation and mindfulness app with a large library of free guided sessions, music, and talks. Under Christopher Plowman it grew into one of the most widely used free meditation apps. It also includes a customizable meditation timer and...

Habitica turns habits, daily goals and to-dos into a role-playing game. Users earn rewards and level up characters for completing tasks, and can team up in parties for accountability.

Streaks is a habit-tracking app for iPhone, iPad and Apple Watch. It encourages daily consistency by helping users maintain streaks across a set of personalized tasks.

Busuu is a language learning platform offering courses in more than a dozen languages. Founded in 2008 by Bernhard Niesner and Adrian Hilti, it combines self-paced lessons with feedback from a community of native speakers. It is available on web and mobile.