[ktosobcy]

Opened the blog... then the main page and I'm still not 100% what it is... looks like collab-editor? but has own format (not markdow or latex)?

[V__]

Typst is an open-source alternative to latex and typst.app is their closed-source collaborative web editor.

[quirino]

It's more of a LaTeX alternative, which also happens to have an official web app.

The engine itself is open source, so you can always just install it and compile your documents on the command line.