ONLYOFFICE (Docs, DocSpace and Desktop Editors)
ONLYOFFICE — the open-source office suite you can host yourself
ONLYOFFICE (by Ascensio System SIA) is a complete office suite — documents, spreadsheets, presentations, PDFs and fillable forms — whose core is open source under AGPLv3 and can be installed on your own server. It ships in three shapes that share one editing engine: ONLYOFFICE Docs, the web editors you embed in your own platform (release 10.0.0, 12 October 2026); ONLYOFFICE DocSpace / Rooms, the room-based collaboration and file platform, in the cloud or on-premises; and ONLYOFFICE Desktop Editors, free offline apps for Windows, macOS and Linux. iOS and Android apps cover mobile.
What separates ONLYOFFICE from most “office alternatives” is that it is OOXML-native: DOCX, XLSX and PPTX are the primary formats, so styles, charts, formulas and layout survive instead of being round-tripped through a foreign internal model. Everything else — ODF, Apple iWork, Visio, WPS, Hangul, e-books — is imported and converted. That is why it is the usual drop-in editing engine behind Nextcloud, ownCloud, Seafile and SharePoint, with 50+ ready connectors in total.
Supported file formats at a glance
“Native” means the file is edited in its own format; “converted” means it is turned into OOXML when opened, which is fast and accurate for normal documents but can shift very complex layouts.
| Editor | Extensions | Depth |
|---|---|---|
| Documents | DOCX, DOCM, DOTX, DOTM, DOC, DOT, ODT, OTT, RTF, TXT, HTML, HTM, MHT, MHTML, XML, HML, EPUB, FB2, FODT, MD, STW, SXW, WPS, WPT, HWP, HWPX, PAGES, GDOC, PDF, DJVU, XPS, OXPS, OFD | DOCX/DOCM/DOTX/DOTM native; ODT, OTT, RTF, TXT, EPUB, FB2, HTML, MD editable with conversion; the rest view + convert |
| Spreadsheets | XLSX, XLSM, XLSB, XLTX, XLTM, XLS, XLT, ODS, OTS, CSV, TSV, ET, ETT, FODS, NUMBERS, SXC, GSHEET | XLSX/XLSM/XLSB/XLTX/XLTM native; ODS, OTS, CSV, TSV, XLS editable with conversion; the rest view + convert |
| Presentations | PPTX, PPTM, PPSX, PPSM, POTX, POTM, PPT, PPS, POT, ODP, OTP, FODP, ODG, DPS, DPT, KEY, GSLIDES, SXI | PPTX/PPTM/PPSX/PPSM/POTX/POTM native; ODP, OTP editable with conversion; the rest view + convert |
| PDF and fixed layout | PDF, PDF/A, DJVU, XPS, OXPS, OFD | PDF edits like a word processor: text, images, layout, annotations, shapes, redaction, passwords, and export to PDF/A-2a |
| Fillable forms | DOCXF (form template you design), OFORM (ready-to-fill form), fillable PDF | Create fields, dropdowns, checkboxes and radio buttons, assign user roles, then share as PDF or DOCX |
| Diagrams | VSDX, VSDM, VSSX, VSSM, VSTX, VSTM | Built-in diagram viewer (view only) |
Download as: a formatted document can be saved as DOCX, DOTX, PDF, PDF/A-2a, RTF, TXT, ODT, OTT, HTML, EPUB, FB2, MD, JPG or PNG; spreadsheets and presentations likewise export to their ODF and PDF counterparts (XLSX/ODS/CSV, PPTX/ODP).
Which programs can ONLYOFFICE replace?
Because the extension list above spans the Microsoft, Google, LibreOffice, Corel, Hancom, Apple and WPS families, a single install often retires several desktop apps at once. This is the mapping from file type to the program you can stop paying for.
| Program you can drop | Why it works | Depth |
|---|---|---|
| Microsoft Word | .doc, .docx, .docm, .dot, .dotx, .dotm, .rtf, .txt, .xml and .mht/.mhtml all open; DOCX is edited natively with styles, track changes, comments and review. | Full |
| Microsoft Excel | .xls, .xlsx, .xlsm, .xlsb, .xlt, .xltx, .xltm plus .csv/.tsv; formulas, pivot tables and charts survive the trip. | Full |
| Microsoft PowerPoint | .ppt, .pptx, .pptm, .pps/.ppsx/.ppsm and .pot/.potx/.potm — slide shows, speaker notes and presenter view included. | Full |
| Microsoft 365 / Office on the web | Real-time co-editing, comments, chat and version history, but with the storage you choose instead of Microsoft's. SharePoint and Teams-adjacent platforms connect through official connectors. | Mostly — advanced enterprise tooling sits in the paid editions |
| Google Docs, Sheets and Slides | .gdoc, .gsheet and .gslides exports open, and Rooms give you the same browser-only, comment-first collaboration model — on your own servers if you want. | Mostly |
| LibreOffice, Apache OpenOffice, Collabora Online | .odt, .ods, .odp, .ott, .ots, .otp, .fodt, .fods, .fodp and the legacy StarOffice formats .sxw, .stw, .sxc, .sxi are imported and converted. It is the alternative editing backend for Nextcloud Office when you do not want a LibreOffice-based engine. | Mostly — ODF is converted, not native |
| Adobe Acrobat (editing, not just reading) | PDFs open in a real editor: edit text, images and layout, annotate, draw, redact, password-protect, fill and create fillable forms, and export PDF/A-2a. Meanwhile DjVu, XPS, OXPS and OFD can at least be read and converted. | Substantial — but not a prepress or OCR-suite replacement |
| Microsoft Visio | .vsdx, .vsdm, .vssx, .vssm, .vstx and .vstm diagrams render in the built-in viewer, so you can read them without a Visio licence. | View only |
| WPS Office, Microsoft Works, WordPerfect | The Chinese WPS family (.wps, .wpt documents; .et, .ett spreadsheets; .dps, .dpt presentations) plus legacy Works .wps and WordPerfect .wpt files open and convert instead of failing. | Import only |
| Hancom Hangul Word Processor | .hwp and .hwpX documents (still common in Korean government, education and corporate paperwork) open and convert. | Import only |
| Apple iWork — Pages, Numbers, Keynote | .pages, .numbers and .key files open and convert, and any document can be exported back to PDF, EPUB or HTML for people who left the Mac behind. | Import only |
| E-book readers and converters | .epub, .fb2 and .djvu are read directly, and any document can be exported as EPUB or FB2 — a Calibre round trip is no longer mandatory. | Read + export |
| Markdown and plain-text editors | .md, .txt, .html and .xml open in the word processor for people who would rather write prose in a real editor. | Mostly — converted on save |
Three ways to run it
- Desktop Editors (free): Windows, macOS and Linux, fully offline, tabbed interface, PDF editing and form creation, plugin marketplace and optional AI tools. Connect it to ONLYOFFICE, Nextcloud, ownCloud, Seafile, Box or Dropbox to co-edit in real time. Free for personal and professional use.
- Docs (self-hosted web editors): install on Docker, Debian/Ubuntu, CentOS or Windows Server 2016+ (AMD64 and ARM64), or use the 1-click apps on DigitalOcean and Cloudron. Bundled Docker Compose images come pre-wired with Nextcloud or ownCloud. Embed the editors into your own product through the Document Server API instead of buying a per-seat SaaS editor.
- DocSpace / Rooms (cloud or on-premises): structured rooms for internal teams, public sharing and virtual data rooms, with role-based permissions, encryption in transit and at rest, SSO (SAML, OAuth, LDAP/AD), watermarking, audit logs, and an MCP server so AI agents can create rooms, upload files and manage users.
AI and integrations
- AI Tools is an optional layer with multi-provider support (any model, including self-hosted ones), MCP and web search: generate, rewrite and translate content, check grammar and style, convert text to visuals, ask questions of your own documents, build custom assistants, recognise tables and assist PDF edits. In the open-source editions it may need a separate installation.
- 50+ connectors reach Nextcloud, ownCloud, Seafile, SharePoint, Mattermost, Slack, Box, Dropbox, Miro, Odoo, Pipedrive, Plone, HumHub, Redmine, WordPress, Directus and Moodle, with Outlook and Thunderbird add-ins and a Telegram bot on top. Java and PHP SDKs plus n8n nodes cover custom builds.
Honest limits
- OOXML is the native format. ODF, EPUB, FB2, HTML, MD, RTF, TXT, CSV, XLS and the Apple, WPS and Hangul families are converted on open, so heavily formatted files can shift. Teams standardised on ODF should keep a LibreOffice install for verification.
- Diagrams and iWork files are not round-trip. Visio (.vsdx and friends) is view-only, and .pages, .numbers, .key, .hwp and .wps are import-and-convert rather than formats you can save back faithfully.
- Community versus Enterprise. The free AGPLv3 Docs Community edition leaves out the administration panel and the mobile web editors; those require a commercial licence. Check the edition comparison before standardising on it.
- AGPLv3 obligations. Exposing ONLYOFFICE Docs to users over a network triggers the copyleft requirements for your modifications — review this before shipping a SaaS.
- Forms use proprietary containers. DOCXF and OFORM are ONLYOFFICE’s own formats; send finished forms as PDF or DOCX to anyone outside the suite.
- Not a universal replacement. No CAD, no Publisher (.pub), no full LaTeX workflow, and very old binary files or heavy VBA macros may render imperfectly. Some niche features (mobile web editors, admin panel, branding removal) are commercial only.
- Cloud and enterprise tiers are paid. The Desktop Editors are genuinely free, but DocSpace/Rooms and the Enterprise/Developer editions are licensed per user or per server.
Links
- Website: https://www.onlyoffice.com
- Docs: https://www.onlyoffice.com/docs
- Desktop Editors: https://www.onlyoffice.com/desktop
- DocSpace / Rooms: https://www.onlyoffice.com/rooms
- Download Community 10.0.0: https://www.onlyoffice.com/download-community
- Maintained format list: https://github.com/ONLYOFFICE/document-formats
- Source code: https://github.com/ONLYOFFICE/DocumentServer
- License: GNU AGPLv3 (Community), commercial (Enterprise / Developer)