OnlyOffice vs Microsoft 365

Why Switch from Microsoft 365 to OnlyOffice?

Microsoft 365 dominates the office productivity market, but that dominance comes with significant concerns. Microsoft processes vast amounts of user data on US servers, and investigations by European data protection authorities — notably the Dutch DPIA findings — have revealed extensive telemetry collection. The European Data Protection Supervisor has flagged Microsoft 365 for EU institutions due to unresolved data transfer concerns.

OnlyOffice, developed by Ascensio System SIA in Latvia, is a full-featured office suite that opens, edits, and saves Microsoft formats (DOCX, XLSX, PPTX) with high fidelity. It is open source, self-hostable, and built with European data protection standards at its core. Unlike LibreOffice, OnlyOffice was designed from the ground up for real-time collaborative editing, making it a genuine replacement for Microsoft 365’s online collaboration features.

For organizations that need Microsoft-compatible documents without Microsoft’s data practices, OnlyOffice offers the most seamless transition path.

Feature Comparison

Feature	OnlyOffice	Microsoft 365
MS format compatibility	✅ Excellent (OOXML native)	✅ Native
Real-time collaboration	✅ Yes	✅ Yes
Self-hostable	✅ Full control	❌ Cloud only
Open source	✅ AGPL v3	❌ Proprietary
Desktop apps	✅ Windows, Mac, Linux	✅ Windows, Mac
Mobile apps	✅ iOS, Android	✅ iOS, Android
Document editor	✅ Full-featured	✅ Full-featured
Spreadsheet	✅ With pivot tables, charts	✅ Advanced (VBA macros)
Presentation editor	✅ Full-featured	✅ Advanced animations
CRM / project tools	✅ Built-in (Workspace)	⚠️ Separate products
Data location	Your choice (self-host) 🇪🇺	United States 🇺🇸 (default)

Pricing

OnlyOffice is significantly more affordable than Microsoft 365:

• OnlyOffice Desktop Editors: Free — full offline editors for documents, spreadsheets, and presentations
• OnlyOffice DocSpace Free: Free — 12 rooms, up to 2 admins, collaboration features
• OnlyOffice DocSpace Business: From €12/admin/month — unlimited rooms, branding, advanced permissions
• OnlyOffice Workspace: From €4/user/month — full collaboration suite with CRM, mail, projects
• Microsoft 365 Business Basic: €6/user/month — web apps only, 1 TB OneDrive
• Microsoft 365 Business Standard: €12.50/user/month — desktop apps + web apps
• Microsoft 365 Business Premium: €22/user/month — advanced security features

OnlyOffice’s free desktop editors alone cover most individual needs. For teams, the self-hosted option eliminates per-user cloud fees entirely — you only pay for your own server infrastructure.

Privacy & Data Sovereignty

OnlyOffice provides genuine data sovereignty options that Microsoft 365 cannot match:

• Open-source code (AGPL v3) means the entire application can be audited for security and privacy
• Self-hosting keeps all documents on your own infrastructure — no data ever leaves your servers
• The cloud version processes data in EU data centers with full GDPR compliance
• No telemetry or diagnostic data is collected without explicit consent
• Ascensio System SIA is a Latvian company, fully subject to EU data protection regulations
• Integration with Nextcloud, ownCloud, and other European platforms for a complete sovereign stack
• No hidden data flows to advertising or AI training systems

Microsoft’s extensive telemetry collection, documented by multiple European DPAs, means that even opening a document sends metadata to Microsoft. OnlyOffice, especially self-hosted, sends nothing.

Migration Guide

Difficulty: Moderate | Estimated time: 1 day for individuals, 1-4 weeks for organizations

1. Evaluate your current Microsoft 365 usage. Audit which Microsoft features your team actually uses. If your workflows rely heavily on VBA macros, Power BI, or Microsoft Teams integration, plan for alternatives or workarounds. For standard document editing, spreadsheets, and presentations, OnlyOffice is a direct replacement.
2. Install OnlyOffice Desktop Editors. Download the free desktop editors for Windows, macOS, or Linux. Open your existing .docx, .xlsx, and .pptx files to verify compatibility. Test your most complex documents to identify any formatting issues before committing.
3. Set up your collaboration platform. For teams, deploy OnlyOffice DocSpace (cloud) or self-host OnlyOffice Workspace on your own server. If you already use Nextcloud, install the OnlyOffice connector app for seamless integration.
4. Migrate your files. Copy your documents from OneDrive or SharePoint to your new platform. Since OnlyOffice uses the same OOXML format natively, no file conversion is needed — your files work as-is.
5. Train your team. OnlyOffice’s interface closely resembles Microsoft Office, so the learning curve is minimal. Focus training on differences like the collaboration features, Spaces in DocSpace, and any workflow changes specific to your organization.
6. Cancel Microsoft 365 subscriptions. Once your team is comfortable and all workflows are migrated, cancel your Microsoft 365 subscriptions. Keep a record of your license count and renewal dates for reference.

Real-World Use Cases

• A Belgian municipal government replaced Microsoft 365 with OnlyOffice self-hosted on Nextcloud to ensure all citizen-related documents stay within their own infrastructure. The OOXML compatibility allowed a seamless transition without requiring staff to learn new file formats, and the self-hosted setup eliminated per-user licensing costs entirely.
• A German startup with 30 employees uses OnlyOffice DocSpace for collaborative document editing, project proposals, and client deliverables. By avoiding Microsoft 365, they save over EUR 4,500 per year in licensing fees while maintaining full compatibility when sharing documents with clients who use Microsoft Office.
• A Polish university department adopted OnlyOffice as the standard office suite for students and faculty, using the free desktop editors for individual work and OnlyOffice Workspace for collaborative research papers. Students graduate with experience in open-source tools rather than vendor lock-in to proprietary software.

Company Background

OnlyOffice is developed by Ascensio System SIA, a company founded in 2009 and headquartered in Riga, Latvia. The company began by building collaboration and project management tools for businesses, and over time expanded its focus to document editing, recognizing the massive market need for an open-source alternative to Microsoft Office that could match its format compatibility.

Ascensio System SIA employs over 200 developers and staff across its Riga headquarters and development offices. The company has deliberately focused on building the best possible Microsoft format compatibility in an open-source office suite — a technical challenge that most competitors have struggled with. By choosing OOXML (the same format family as .docx, .xlsx, .pptx) as OnlyOffice’s native format rather than the ODF format used by LibreOffice, Ascensio achieved superior fidelity when opening and saving Microsoft documents. This engineering decision has been central to OnlyOffice’s appeal for organizations migrating from Microsoft 365.

OnlyOffice has grown to serve millions of users worldwide, with particularly strong adoption in education, government, and enterprise sectors. The platform has been deployed by organizations including UNESCO, the Italian government, and numerous European universities. The software is published under the AGPL v3 open-source license, and the community edition is freely available for self-hosting. Ascensio’s Latvian headquarters means the company operates within the EU, subject to GDPR and European data protection law — an important distinction from US-based productivity suites that process documents on American servers.

Security & Compliance

OnlyOffice provides security features appropriate for enterprise and government deployment:

• Open-source code (AGPL v3) — the entire editor codebase is published on GitHub, allowing organizations, security researchers, and government agencies to perform their own security audits
• Self-hosting capability — organizations can deploy OnlyOffice entirely on their own infrastructure, ensuring documents never leave their controlled environment
• End-to-end encryption for rooms in OnlyOffice DocSpace, providing an additional layer of protection for sensitive documents
• JWT (JSON Web Token) authentication for securing communications between the document server and the integration platform (Nextcloud, ownCloud, etc.)
• GDPR compliant as an EU-based company, with data processing agreements available for cloud customers and built-in tools for data subject access requests
• Two-factor authentication (2FA) with TOTP support for securing DocSpace and Workspace accounts
• Granular access permissions with role-based access control at the room, folder, and document level — supporting editor, reviewer, commenter, and viewer roles

Integration Ecosystem

OnlyOffice stands out for its exceptional integration capabilities with other platforms:

• Official Nextcloud integration — the most popular document editing connector for Nextcloud, enabling real-time collaborative editing of office documents directly within the Nextcloud interface
• ownCloud, Seafile, and Moodle integrations — official connectors for these platforms, extending OnlyOffice’s collaborative editing to various European cloud and learning management systems
• WOPI protocol support for integration with platforms that implement the Web Application Open Platform Interface, enabling broad compatibility
• Comprehensive REST API for DocSpace and Workspace, enabling custom integrations, automation workflows, and third-party application development
• Desktop editors for Windows, macOS, and Linux that work offline and sync with cloud platforms — also available as a Snap, Flatpak, and AppImage on Linux
• Mobile apps for iOS and Android for viewing and editing documents on the go, with offline support
• Macro and plugin support using JavaScript, allowing users to extend editor functionality with custom scripts and community-developed plugins
• Document conversion API for server-side batch conversion between formats (DOCX, ODT, PDF, EPUB, HTML, TXT, and more) — useful for automated document processing pipelines

Who Should Switch?

OnlyOffice is ideal for:

• EU organizations needing GDPR-compliant document collaboration with data sovereignty guarantees
• Government agencies and public sector bodies that cannot send document data to US servers
• Businesses looking to reduce per-user licensing costs without sacrificing Microsoft format compatibility
• Nextcloud users who want a tightly integrated, self-hosted office suite
• Open-source advocates who want a transparent, auditable productivity platform

The Bottom Line

OnlyOffice is the closest thing to a drop-in replacement for Microsoft 365 in the European open-source world. Its native OOXML support means documents look right when opened in Microsoft Office and vice versa. The self-hosting option provides genuine data sovereignty that Microsoft 365 fundamentally cannot offer.

The gap is in the ecosystem: Microsoft’s macro support, advanced Excel features, and the Teams integration make it deeply entrenched in many organizations. If your workflows depend on VBA macros or deep Microsoft integrations, the switch will require effort. But for document creation, collaboration, and standard business use, OnlyOffice delivers everything most organizations need — at a fraction of the cost and with full control over your data.

Frequently Asked Questions

Can OnlyOffice open and save Microsoft Office files without formatting issues?

OnlyOffice uses OOXML (the same format family as .docx, .xlsx, .pptx) as its native format, which gives it the best Microsoft compatibility among open-source office suites. Most documents will look identical. Very complex spreadsheets with VBA macros or advanced PowerPoint animations may require adjustments.

Can I self-host OnlyOffice on my own server?

Yes. OnlyOffice offers a Community Edition that can be self-hosted for free on your own infrastructure. The Enterprise Edition adds advanced features like LDAP, SSO, and audit trails. Self-hosting gives you complete control over your data — it never leaves your servers.

How does OnlyOffice compare to LibreOffice?

While both are open-source, OnlyOffice is built for real-time collaborative editing in the browser (similar to Google Docs), whereas LibreOffice is primarily a desktop application. OnlyOffice also has superior Microsoft format compatibility since it uses OOXML natively, while LibreOffice uses ODF as its default format.

Does OnlyOffice integrate with Nextcloud?

Yes. OnlyOffice has an official Nextcloud integration that allows you to create, edit, and collaborate on documents directly within Nextcloud. This combination provides a fully self-hosted, GDPR-compliant alternative to both Microsoft 365 and Google Workspace.

Is OnlyOffice suitable for a large organization with hundreds of users?

Yes. OnlyOffice Enterprise Edition supports large-scale deployments with features like Active Directory/LDAP integration, single sign-on (SSO), multi-tenancy, and dedicated support. Organizations with hundreds or thousands of users can deploy it on-premises or in a private cloud.