Duolingo - Duolingo is a free language learning app for iOS, Windows and Android devices. The app makes learning a new language fun by breaking learning into small lessons where you can earn points and move up through the levels. Read more about Duolingo.

Hiver - Manage Customer Support, Sales and Projects right from your Gmail inbox. Collaborate with Shared Labels, Shared Contacts, email notes, email reminders and email templates

Mondly - Learn 33 languages in 500 bite-size lessons and 14 conversational modules.

Clean Email - Clean Email is an online service that empowers you to take control of your mailbox.

Lingvist - Lingvist helps you take your foreign language skills to the next level with a broad selection of exercises and lessons.

Nylas Mail - The Nylas Cloud API powers your application with email, calendar & contacts features. Built-in features for better email, calendar, and contact management.