[Petrakis]

This is unorthodox, but I use https://www.overleaf.com/ its a neat online editor where I can have my docs stored on the cloud and it has a PDF preview on the side, and you can compile it at the end.

[erk__]

While it is not advertised much on their own site Overleaf is AGPL3 licensed and is mostly open source: https://github.com/overleaf/overleaf

[lucakiebel]

Overleaf is great, I use a self hosted instance with my company. Only downside to self hosting is that the git integration does not work