Jottr is a simple, web-based, real-time notes app.
I created Jottr when I was first taking a deep dive into React, moving beyond a handful of simple components within an existing project into a fully fledged React app with a database, authentication, state management and so on.
Behind the scenes I run a Node.js/Express backend for the app which communicates with a remote MongoDB database and exposes an API to allow for the usual create/read/update/delete operations.
As much as it looks a little dated now, and lacks a lot of basic features users would expect from a Notes app, I was always proud of this project - everything which is there feels really solid, from the authentication tech right through to the UX of managing notes. I particularly liked my save buffering system which, instead of pinging the server consantly with your updates, waits until you've stopped typing for a second and then syncs things up, always showing you the status in the corner - either Modified, Saving or Saved.