BeneTalk - Speech coach for people who stutter by people who stutter

Dialogflow - Conversational UX Platform. (ex API.ai)

LingRoom.pl - Tutoring marketplace LingRoom pairs students with private tutors, either locally in-person or online via Skype. Find your best tutor.

Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.

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.

Botkit - Botkit is an open source developer tool for building chat bots, apps and custom integrations for major messaging platforms.