ONLYOFFICE Desktop Editors v7.4 is already available, offering the majority of the improvements of ONLYOFFICE Docs v7.4. Read this post to find out more.
ONLYOFFICE Desktop Editors v7.4 released: form templates gallery, plugin manager, new print settings and more.
Isn’t OnlyOffice proprietary software?
You’re thinking of FreeOffice.
Nope, it’s open source under AGPL3. I think they might be dual-licensing though as AFAIK you have to pay if you use it as an enterprise.