LibreOffice is the best free office suite on the desktop, and is now available on Android as a native application. LibreOffice Viewer supports many document formats:
• Open Document Format (odt, ods and odp)
• Microsoft Office 2007–2016 (docx, xlsx and pptx)
• Microsoft Office 97–2003 (doc, xls and ppt)
LibreOffice Viewer also comes with a preview of the editing functionality, which is considered an experimental feature and not stable enough for mission critical tasks. (Visit the Settings to enable this feature.)
Feedback and bug reports are very welcome, to help developers improve the quality of the application on its way to being a full-featured editor. You can report bugs and attach files that trigger them here: https://bugs.documentfoundation.org
LibreOffice Viewer is using the same engine as LibreOffice for Windows, macOS and Linux. This, combined with a new front end based on Firefox for Android, reads documents similarly to LibreOffice on the desktop.
LibreOffice Viewer is released under the Mozilla Public License v2. The software is backed by a dynamic community, represented by The Document Foundation, a not for profit entity based in Germany.
Credits: LibreOffice Viewer has been developed by Collabora and Igalia, backed by Smoose, with contributions from Google Summer of Code students, in joint cooperation with The Document Foundation and the LibreOffice community. SUSE has provided a key foundation of cross platform support, and Mozilla Corporation several core components. Special thanks to hundreds of independent LibreOffice contributors, who have contributed to the source code since 2010.
LibreOffice was based on OpenOffice.org (commonly known as OpenOffice). Full credits: https://www.libreoffice.org/about-us/credits