Office

Two “office” plugins supported:

Collabora - it works like thin client to real LibreOffice instance running on server. Document is handled on server side, so huge document can impact server performance (especially when multiple users opens multiple huge documents). Offers all feature like normal LibreOffice.
OnlyOffice - editor is running on client browser. Backends only server document content, performs conversions, preview etc. Features are limited to OnlyOffice product but it better handles M$ documents.