LibreOffice

LibreOffice is a free, open-source office suite by The Document Foundation. It comes pre-installed on most Linux distributions.

• Writer (documents), Calc (spreadsheets), Impress (presentations), Draw, Base, Math
• Compatible with Microsoft Office formats
• Runs completely offline, with no tracking or data collection
• Windows, macOS, Linux
• Active development and regular updates

It has no subscription and no telemetry, and is a privacy-respecting alternative to Microsoft Office.