How to Migrate from Microsoft 365 to Nextcloud + OnlyOffice

Why Migrate from Microsoft 365?

Microsoft 365 is dominant in European business computing. It’s also a US-headquartered service whose “EU Data Boundary” claims don’t fully address CLOUD Act exposure (Microsoft Corporation retains corporate control of Microsoft Ireland and other EU subsidiaries).

For European businesses where sovereignty matters operationally — public sector, regulated industries, B2B SaaS serving European enterprises, organizations under DORA or NIS2 — the question isn’t whether Microsoft’s compliance posture is adequate. It’s whether to architect around Microsoft entirely.

Nextcloud Hub + OnlyOffice is the European answer. Self-hostable, used by the German government, French government, multiple EU institutions, and dozens of European universities. The combination provides a complete Microsoft 365 alternative: file storage, collaborative documents, email integration, video calls, chat, calendar, contacts, project management.

This is the most ambitious migration in our guide series. Most European SMBs that complete it report it was harder than expected and worth more than expected.

Detailed Migration Steps

Step 1: Hosting Decision (Critical Architecture Choice)

Three hosting paths, with significantly different operational implications:

Option A: Managed Nextcloud (recommended for most SMBs)

Provider hosts and operates Nextcloud for you. You manage users and content; they manage infrastructure.

• Hetzner Storage Share: ~€2-8/user/month. German jurisdiction, strong sovereignty.
• Infomaniak kSuite: ~€6-12/user/month. Swiss jurisdiction, hydroelectric infrastructure.
• OwnCloud Online or other Nextcloud-managed providers: various.

Pros: no infrastructure operations burden. Cons: less customization, slightly higher per-user cost at scale.

Option B: Self-hosted Nextcloud on Hetzner (for technical teams)

You run Nextcloud on your own infrastructure.

• Hetzner Cloud server: ~€20-100/month base + storage costs
• Nextcloud + OnlyOffice + Talk: open-source, no software licensing
• Operations cost: realistic estimate is 10-20% of one engineer’s time ongoing

Pros: full sovereignty, dramatic cost savings at scale (80+ users), full customization. Cons: real operational burden.

Option C: Self-hosted with managed support (enterprise)

You run Nextcloud, but with vendor support contracts. Nextcloud GmbH (Stuttgart) and various partners offer enterprise support.

For most European SMBs (10-200 employees), Option A is the right starting point. The cost premium over self-hosting is real but worth it for operational simplicity. Consider Option B for organizations with strong DevOps capability or 100+ employees where economics favor it.

Step 2: Inventory Microsoft 365 Environment

Before migrating, document:

• Users: total count, license types
• OneDrive storage: per-user storage, total volume
• SharePoint sites: count of sites, total volume, permission structures
• Mailboxes: sizes, retention requirements
• Teams: number of channels, active vs archived, file shares
• External sharing patterns: external users, shared links
• Integrations: third-party apps connected, automation flows (Power Automate)
• Compliance configurations: retention policies, eDiscovery requirements

This document determines your migration scope and timeline. Bigger Microsoft 365 environments require longer parallel-run periods and more careful per-team migration.

Step 3: Provision Nextcloud

For managed hosting, signup is straightforward — provision instance, configure admin account, basic setup.

For self-hosted, the working setup we recommend:

Hetzner CCX23 (4 vCPU, 16 GB RAM): €30/month
Hetzner Volume (1-5 TB depending on usage): €5-25/month
Backup: Hetzner Storage Box for off-server backup: €4-10/month
Domain + Let's Encrypt SSL: included

Total infrastructure: ~€50-100/month for an organization of 50-200 users.

Software stack:

• Nextcloud Hub (latest version)
• OnlyOffice Document Server
• Nextcloud Talk for video calls
• collabora online (alternative to OnlyOffice if preferred)

Use Docker Compose or Nextcloud’s All-in-One installer to simplify setup.

Step 4: Migrate Email Separately

Email is the most-painful part of Microsoft 365 migration but conceptually separate from Nextcloud. Choose your email destination first:

• Proton Mail Business (Switzerland): ~€7-12/user/month
• Mailbox.org (Germany): ~€1-9/user/month
• Tutanota (Germany): ~€3-12/user/month

Use email migration tools to move from Exchange Online to your chosen destination. Most providers offer migration assistance.

Step 5: Migrate OneDrive / SharePoint

For file migration, three approaches:

Approach A: Manual download/upload (small migrations only) Download from OneDrive/SharePoint, upload to Nextcloud. Works for <100 GB total, small user counts.

Approach B: Nextcloud’s external storage feature Connect OneDrive as external storage in Nextcloud during transition. Files remain in OneDrive but accessible through Nextcloud. Allows gradual migration.

Approach C: Bulk migration via Rclone For larger migrations, use Rclone to copy from OneDrive/SharePoint to Nextcloud’s data directory. Preserves directory structure and metadata. Requires server-side access for self-hosted; harder for managed.

For a 50-user organization with 5-10 TB total, Approach C is typically necessary and takes 1-2 weeks of focused work.

Step 6: Set Up OnlyOffice Integration

OnlyOffice integration in Nextcloud is the killer feature for Office migration:

1. Install Nextcloud Office app (uses OnlyOffice Document Server)
2. Configure OnlyOffice connection
3. Test with .docx, .xlsx, .pptx files

Result: users can open and collaboratively edit Microsoft Office files directly in browser. Real-time multi-user editing works. Format compatibility is excellent for typical business documents.

Caveats:

• Very complex Excel files with macros need testing (most work, edge cases break)
• Custom Office add-ins don’t transfer
• Some PowerPoint animations render differently

Step 7: Replace Teams

Microsoft Teams replacement is the hardest part because Teams combines chat + video + file sharing + project management.

Recommended split:

• Nextcloud Talk for video calls (small to medium teams)
• Self-hosted Element/Matrix server for persistent team chat (better than Nextcloud Talk for chat-heavy teams)
• Nextcloud Files + Groupfolders for file sharing
• Nextcloud Deck for kanban/project management

This is more complex than Teams’s all-in-one model but each piece is better than Teams’s equivalent. The complexity is the price of sovereignty.

For organizations of 200+ users, additional infrastructure investment (dedicated Matrix server) makes sense.

Step 8: Replace SharePoint with Groupfolders

Nextcloud Groupfolders are the SharePoint equivalent — team-shared spaces with role-based permissions.

For each SharePoint site:

1. Create Groupfolder in Nextcloud
2. Configure permissions matching SharePoint structure
3. Migrate files via Rclone or manual copy
4. Communicate new path to team

The mental model is simpler than SharePoint (no separate sites/lists/libraries — everything is files and folders). Some teams prefer this; some find it limiting. Plan for adjustment time.

Step 9: SSO and Identity Integration

For organizations of 50+ users, configure SAML SSO:

• Self-hosted Keycloak (open source, EU-deployable) as identity provider
• Or Authentik (open source, simpler than Keycloak)
• Or commercial EU IDP like Signicat

This unifies authentication across Nextcloud, Element, GitLab, Mattermost, and other self-hosted tools. Users get one login; admins get one place to manage access.

Step 10: Phased Cutover

The single most important migration tip: do not big-bang cutover.

Successful pattern:

1. Week 1-2: Pilot team (5-10 users) on Nextcloud full-time
2. Week 3-4: Refine setup based on pilot feedback
3. Week 5-8: Migrate one team per week
4. Week 9-12: Final teams + edge-case users
5. Week 13-16: Microsoft 365 read-only period for reference
6. Week 16+: Cancel Microsoft 365

Faster timelines fail. Slower timelines work but consume project momentum.

Step 11: Cancel Microsoft 365

After all teams confirmed on Nextcloud:

1. Export final data from M365 for compliance archive (typically 7+ year retention)
2. Cancel Microsoft 365 subscription
3. Update internal documentation
4. Communicate to external collaborators about new workflow

Tips for a Smooth Migration

• Email migration is the hardest single piece. Plan it carefully; consider hiring migration specialists if budget allows.
• Power users will struggle most. People who use Microsoft 365 deeply (advanced Excel users, Power Automate creators, SharePoint admins) face the biggest adjustment. Acknowledge this; provide training time.
• The cost economics are real but require self-hosting. Managed Nextcloud at €5-12/user/month vs M365 at €11.50-20/user/month is cost-neutral. Self-hosted Nextcloud is dramatically cheaper at scale.
• OnlyOffice format compatibility is excellent for typical business documents. Power users with complex spreadsheets or presentations need testing.
• Teams replacement is complex. Nextcloud Talk + Element + Files works but isn’t the all-in-one Teams pattern. Some teams prefer the modular approach; some don’t.
• Compliance archive is non-negotiable. Whatever your retention requirements, plan compliance archive before cancellation.
• Plan for change management, not just technical migration. This is an organizational project. The technical work is 30-40% of the total effort; communication, training, and change management are the rest.
• Public sector adoption proves the model works. German federal government, French government, Italian Ministry of Defence, and many EU institutions run on Nextcloud. If they can do it, your organization can too — but they spent years on the migration, not weeks.