File fidelity, not the writing experience, is what makes or breaks a move off Microsoft Office. Ordinary documents, plain spreadsheets, and simple slide decks move with little drama, but heavily formatted reports, mail merges, tracked-review cycles, linked workbooks, and macro-driven spreadsheets are where a switch either holds or breaks. Test those first, then decide whether you need the suite to be your primary editor for .docx, .xlsx, and .pptx files, or whether new work can standardize on open formats and export final copies to PDF.
For the core Word, Excel, and PowerPoint work, two full office suites lead the list and answer different needs. ONLYOFFICE Docs is built around Office Open XML compatibility and real-time collaboration, and it self-hosts on your own servers, so it fits teams that still exchange .docx and .xlsx files with outsiders and want browser coauthoring without a Microsoft 365 account. LibreOffice is the deeper desktop suite - Writer, Calc, Draw, and Impress - and works offline as local files, which suits individuals and organizations that value a full-featured editor over live coauthoring. The rest of the list covers the parts of Office beyond the document suite: SOGo for Outlook-style mail, calendars, and contacts, and GanttProject, LibrePlan, and TaskJuggler for the project scheduling many people lean on Excel or Project for. The gaps to expect in the suites are exact fidelity and automation: fonts substitute, pagination shifts, and VBA macros are usually where a quick switch becomes a small development project.
Treat migration as inventory and cleanup, not a bulk convert. Keep your original .docx, .xlsx, and .pptx files as source records, then rebuild templates, mail-merge sources, and slide masters intentionally rather than trusting conversion. Move long-lived internal files to an open format, export finalized records to PDF, and run pilot migrations department by department while keeping a fallback path for files that must round-trip with Microsoft Office users.
