LibreOffice is a cross-platform, open-source office software suite from The Document Foundation that offers word processing, spreadsheets, presentations, a drawing application that does 3D, a database front-end, and file compatibility with Microsoft Office and other formats. (See LibreOffice vs. Microsoft Office feature comparison for more details.) The current LibreOffice version is “a feature-rich major release of the LibreOffice 6 family with better performance, a large number of new and improved features, and enhanced interoperability with proprietary document formats.”
LibreOffice 6.4.2 is a free, donationware download for OS X 10.10 and up (with a separately installed Java Runtime Environment (JRE) required for some features, notably the database front-end, Base), and it runs on Windows and Linux, as well.
The latest LibreOffice release notes mention that “Mac users will be happy to know that the issue of blurry fonts on Retina displays has been resolved.”
LibreOffice 6.3.5 is a more mature version recommended for enterprise, corporate environments and more conservative users who don’t need all the very latest features. (See also: LibreOffice security updates.)
LibreOffice Online is available as a Docker image, “which provides basic collaborative editing of documents in a browser by re-using the LibreOffice core; rendering fidelity should be excellent, and interoperability match that of LibreOffice” for those willing to set up the necessary host platform.