Outline : Team wiki, documentation, meeting notes, playbooks, onboarding, work logs, brainstorming, & more…
Mailtrain : Mailtrain is a self hosted newsletter application built on Node.js (v5+) and MySQL (v5.5+ or MariaDB). Mailtrain supports subscriber list management, ...
Commento : A lightweight, open source, tracking-free comment engine alternative to Disqus.
cal.com : Open source meeting scheduling tool. Send a link, let others book a slot. Calendly alternative.
Documize is an open source modern, lightweight and comprehensive alternative to Confluence.
It's built with Golang + EmberJS and compiled down to a single executable binary for Linux, Windows and macOS.