LibreOffice uses the OpenDocument Format (ODF), a fully open and ISO standardised file format that guarantees access to your data forever. (You can, of course, encrypt your documents with a password.)
What is ODF file?
The Open Document Format (ODF) is an XML-based open source file format for saving and exchanging text, spreadsheets, charts, and presentations. Files saved under ODF, termed “OpenDocuments,” have easily recognizable extensions, similar to Microsoft’s proprietary .
What can open ODF files?
Files in ODF format can be opened with OpenOffice.org and LibreOffice in Mac Os, Microsoft Windows and Linux platforms.