StreamSaver.js

This! It is frustrating that web apps like draw.io can't save to file directly using Firefox. It gets old having to save a new file every time you make a change. Beyond that, the File System API would also allow for streamed downloads directly from the web-app. This would allow for web-apps to generate large download files without having to store a copy on a database (external server or IndexedDB), which is a privacy improvement. The only way to do this now is by using convoluted techniques to essentially do a MITM to a fake endpoint [1]. [1] https://github.com/jimmywarting/StreamSaver.js