AppFlowy - AppFlowy is an open source alternative to Notion. You are in charge of your data and customizations.
Documize - Enterprise-grade wiki and knowledge management platform
Notion - All-in-one workspace. One tool for your whole team. Write, plan, and get organized.
HackMD - Fast and flexible, real-time collaborative markdown, inspired by Hackpad.
Wikipedia - Wikipedia is a free online encyclopedia, created and edited by volunteers around the world and hosted by the Wikimedia Foundation.
ReadTheDocs - Spend your time on writing high quality documentation, not on the tools to make your documentation work.