OnlyOffice
Latvia
Open-source office suite from Latvia with a browser-based editor that closely mirrors Microsoft Office's interface.
European Alternative to:
An office suite from Ascensio System SIA, headquartered in Riga. OnlyOffice has been around since 2009 and is unusual in that its document, spreadsheet and presentation editors were built from the ground up around the OOXML format, so MS Office files round-trip with very little drift.
What you get
- Docs: word processor, spreadsheet and presentation editor with live collaboration
- A self-hosted Docs server (Community Edition is free, Enterprise is paid) plus a hosted SaaS option
- Workspace, the bigger bundle that adds mail, projects, CRM and a calendar
- Native desktop and mobile apps that sit on top of the same engine
- Integrations with Nextcloud, ownCloud, Seafile, Confluence, Moodle and many more
Where it sits
The company is based in Latvia and operates under EU law. The Docs Community Edition source is on GitHub under AGPL, which is part of why so many other platforms embed it. There is a Russian-language history to the team that's worth knowing about; the EU legal entity and the current development are based in Riga.
Honestly
OOXML fidelity is the standout feature: if you live in Word and Excel files, OnlyOffice handles them better than most open-source competitors. The licensing is more commercial than LibreOffice (per-user fees on the supported tier), but for organisations that need MS-compatible collaboration without sending documents to Microsoft, it's a serious option.
Germany
France