The European Alternative to Microsoft 365 & Google Workspace
A complete office suite deployed on your own infrastructure. Files, Talk, Mail, Calendar, Office editor — all self-hosted, open source, and GDPR-compliant. Your data never leaves your servers.
Built on Nextcloud — Europe's Leading Open-Source Platform
Trusted by millions of users and organizations worldwide.
10,100
GitHub Stars
8,600+
Commits
AGPLv3
Free & Open Source
Germany
EU-Based Company
Everything Microsoft 365 Offers — Without Microsoft
Nine core applications that replace your entire office suite, deployed on your infrastructure.
Files
Sync, share, and version files. Desktop clients (Windows, Mac, Linux) plus mobile apps (iOS, Android). Replaces OneDrive, Google Drive, and Dropbox.
Office Editor
Edit Word, Excel, and PowerPoint directly in your browser — no Microsoft Office installation needed. Documents never leave your server.
Talk
Video calls, chat, and screen sharing. WebRTC with TURN server, end-to-end encrypted. Replaces Teams, Zoom, and Slack.
Calendar
CalDAV-compatible calendar. Syncs with all devices. Shared calendars, scheduling, and reminders. Replaces Outlook and Google Calendar.
Contacts
CardDAV-compatible unified contact list. Syncs across all devices. Replaces Outlook Contacts and Google Contacts.
Webmail client that connects to your existing IMAP/SMTP server. Replaces Gmail and Outlook webmail.
Deck
Kanban task boards for teams. Track projects, sprints, and to-dos. Replaces Trello and Jira.
Forms
Create questionnaires and collect responses. GDPR-compliant — data stays on your server. Replaces Google Forms.
Whiteboard
Real-time collaborative drawing and brainstorming. Replaces Miro and Mural.
Optional — One Click Away
Powerful add-ons that enhance security and productivity.
ClamAV Antivirus
Automatic virus scanning for every uploaded file. Daily signature updates. Protection against ransomware and malware.
Full-Text Search
Elasticsearch-powered search across document contents. Find any file instantly by its content.
Borg Backup
Automatic, encrypted, deduplicated backups. Configurable retention. Remote backup capability. Business continuity guaranteed.
AI Assistant
Local AI — document analysis, summaries, smart suggestions. Queries never leave your server. Your data does not train external models.
Trusted by European Governments & Organizations
Over 100 million users worldwide use Nextcloud. The platform is translated into 50+ languages.
| Organization | Country | What They Do |
|---|---|---|
| ITZBund | Germany | Central IT agency of the German Federal Government — modern, user-friendly online collaboration |
| Ministry of Interior | France | Secure solution from the leading European provider |
| Deutsche Telekom | Germany | Enterprise deployment at scale — 85,000 users |
| Sorbonne Université | France | Academic use in research environment — 55,000 students |
| Serbian Parliament | Serbia | Government use with high security requirements |
| City of Geneva | Switzerland | Municipal services for citizens — 500,000 residents |
| Amnesty International | Global | Protection of sensitive data at global scale |
Legal Compliance — The Complete Framework
Built for European regulatory requirements — not as an afterthought.
GDPR (2016/679)
Data stays within the EU. On-premise installation — your data remains in your building. Server-side + client-side end-to-end encryption. Full data portability (CalDAV/CardDAV/WebDAV).
NIS2 (2022/2555)
On-premise physical security — server in your building. Air-gap capable. Borg Backup for disaster recovery. Integration with SIEM for 24/7 monitoring and full audit logs.
Schrems II (2020)
The EU Court ruled transatlantic data transfers via US cloud violate GDPR. Sovereign Office uses a 100% EU technology stack — no data ever crosses the Atlantic.
US CLOUD Act — Zero Risk
Microsoft 365 and Google Workspace store data on US servers — subject to US CLOUD Act and FISA. With Sovereign Office on-premise, your data is outside US jurisdiction.
Security Features & Technical Capabilities
Enterprise-grade security for public sector and regulated industries.
LDAP / AD / SSO
Connect to your existing authentication system. SAML, OIDC, OAuth support. Employees use existing credentials — no new passwords.
End-to-End Encryption
Client-side encryption for sensitive files. Keys only exist on the user's device. Even the administrator cannot read encrypted files.
A+ Security Scan
Nextcloud scores A+ on independent security audits. HTTP Security Headers, CSP, HSTS, X-Frame-Options — professional security level.
Brute Force Protection
Built-in rate limiting. Automatic IP blocking after multiple failed attempts. Protection against password-guessing attacks.
ClamAV Antivirus
Automatic scanning of every uploaded file for malware. Updated daily with new signatures. Protection against ransomware and malware.
Versioning & Trashbin
Every file change is saved as a version. Deleted files remain in the trash for a configurable period. No file is ever truly lost.
Borg Backup
Automatic, encrypted, deduplicated backups. Configurable retention. Remote backup capability. Data recovery even if the server is destroyed.
Audit Logs & Monitoring
Complete history: who viewed, edited, shared, or deleted every file. Full transparency and traceability for regulatory compliance.
Cost Comparison — 100 Users / Year
Sovereign Office is AGPLv3 — free software. You pay only for installation, support, and your own hardware.
| Feature | Sovereign Office | Microsoft 365 | Google Workspace |
|---|---|---|---|
| Cost | ~€10,000 (one-time + annual support) | ~€27,360 / year | ~€16,560 / year |
| Open Source | Yes (AGPLv3) | No | No |
| Data Location | Your servers | Microsoft cloud (US) | Google cloud (US) |
| GDPR & Schrems II | By design | At risk | At risk |
| Vendor Lock-in | None — open standards | Strong | Strong |
Bytsecure Value Add — What We Offer
Beyond the open-source software. We deliver a complete sovereignty service.
Physical Installation
On-premise deployment in your organization or at Scaleway EU Cloud. Complete physical data sovereignty. Installation, hardening, NIS2 compliance.
Migration
Secure data transfer from Microsoft 365 (SharePoint, OneDrive, Exchange) and Google Workspace. We handle the complexity — you keep your data.
Configuration & Branding
Your logo, your colors. LDAP/AD/SSO integration. Workflow setup. Everything configured to your organization's identity.
AI Integration
Deployment of the AI Assistant — document analysis, summaries, smart search. AI runs locally — your data does not train external models.
Sovereign SIEM
24/7 security monitoring. Real-time alerts for unauthorized access, data leaks, brute force attacks. Integration with audit logs.
Compliance Package
Complete NIS2/GDPR/Schrems II documentation. Ready-to-submit audit documents. Compliance mapping for your organization.
Training
Administrator training (1-2 days) and end-user workshops, guides, and onboarding. Smooth transition for your entire team.
24/7 Support
Monitoring, updates, troubleshooting, backup restoration. Greek team — response within 4 hours. Everything in your language.
Ready for Digital Sovereignty?
Book a live demo. See how the Sovereign Office Suite replaces Microsoft 365 — on your own infrastructure.