This is an excellent post that takes you along on the author’s journey to build a simple, collaborative (desktop-like interactions and realtime collaborations, such as Notion, Discord, Figma, etc.) todo app:
With the help of many great tools, we’ve successfully built a fast, collaborative todo app. More importantly, we’ve worked out a reasonably simple approach to building similar web apps. As the user base and feature set grow, this approach shall scale well in both performance and complexity.