tus - Open Protocol for Resumable File Uploads
Nowadays, more and more people share photos and videos from their devices. However, choppy mobile networks interrupt these file uploads time to time. tus is a simple and extensible protocol for resumable file uploading built on top of the HTTP. It describes how to resume/terminate an interrupted upload. The spec is here: https://tus.io/protocols/resumable-upload.html
Gitless
Gitless aims to provide a pretty simple and friendly command line interface with the gl command that wraps Git. Since Gitless is built on top of Git, you can always back to Git. Of course, you can keep sharing a repository with your team members.
Service Workies
Learn Progressive Web App and Service Workers with a game that works on web browsers. It is free so far.