Nextcloud Hub: Office Alternative On-Prem

The question “Can we replace Microsoft 365?” comes up in the mid-market more often than five years ago. Reasons: licensing costs (see VMware 2026 discussion), data-protection concerns with US cloud providers, regulatory requirements (NIS2, Schrems-II aftermath, sovereignty debate).

Nextcloud Hub is the most popular open-source alternative — a modular suite bundling files, communication, office, mail and project tools on-prem or on private cloud infrastructure. This article sets out soberly what the suite delivers, where the limits are and what a realistic SMB architecture looks like — interlocking with TrueNAS as a storage backend.

What Nextcloud Hub comprises

Nextcloud is primarily a file sync-and-share platform with an app architecture that exposes extra capabilities as modules. The modules officially bundled as “Hub”:

Module	Function	M365 counterpart
Files	File storage, sync, sharing, federation	OneDrive + SharePoint
Talk	Chat, video conference, screen share	Teams
Office (Collabora or OnlyOffice)	Real-time collaborative office documents	Word/Excel/PowerPoint Online
Mail	IMAP client (no mail server)	Outlook Web
Calendar	CalDAV calendar with sharing	Outlook Calendar
Contacts	CardDAV contacts	Outlook Contacts
Deck	Kanban boards	Planner
Forms	Online forms and surveys	Microsoft Forms
Tables	Database tables for teams	Lists / Loop components

Additionally there is an app store with hundreds of community apps — from bookings (appointment scheduling) through notes to mind-maps and whiteboards. Quality varies; the core Hub modules are all maintained by Nextcloud GmbH or close partners (Collabora).

Files: the foundation

The file module is the mature core. Capabilities:

• Desktop sync clients for Windows, macOS, Linux
• Mobile apps for iOS and Android with auto-upload (smartphone photos)
• Web UI with drag-and-drop
• Internal sharing (permissions per user/group, with expiry, password, upload- or read-only)
• External sharing (public links with password)
• Federation — sharing across separate Nextcloud instances (e.g. with a partner company)
• Versioning with configurable retention
• Full-text search across content (with Solr/Elasticsearch backend; similar idea to TrueNAS Spotlight)

Realistic assessment: Files is absolutely production-ready as a storage platform. Performance depends heavily on server sizing and the storage backend.

Talk: chat and video

Talk is Nextcloud’s answer to Teams/Zoom. Features:

• 1:1 and group chat
• Video conferences (up to 100+ participants with HPB server)
• Screen sharing
• File sharing in chat
• Federated chat across instances
• Mobile and desktop apps

Realistic assessment: Talk works well for most SMB use cases — internal meetings, customer calls, screen support. For large conferences (50+ participants in one video) a dedicated high-performance backend (HPB) with Janus or the Nextcloud HPB server is required. Without HPB, Talk is reliable in small groups (up to ~10); above that, it gets shaky.

Compared to Teams: the real-time features (reactions, breakout rooms, background filters) are less mature. If you hold 90 % of your meetings with 3–5 people, you’ll hardly notice.

Office: Collabora or OnlyOffice

Real-time collaborative editing of office documents is the most delicate point versus M365. Two options:

• Collabora Online (CODE / Collabora Office) — based on LibreOffice, rendered as a web app
• OnlyOffice Docs — own codebase, better MS Office compatibility, but commercial license cost for larger setups

Realistic assessment:

• DOCX, XLSX, PPTX open and edit — works
• Complex formatting (Track Changes with reviewer comments, embedded charts, pivot tables with slicers, complex macros) — partially or not at all
• Real-time collaboration (multiple cursors simultaneously) — works in CODE and OnlyOffice, but less smooth than Word Online
• Mobile — more limited than M365

If you regularly work on complex Excel models with Power Pivot and VBA macros, Collabora will not satisfy you. If you do 80 % of your office work with standard documents (letters, simple tables, presentations), you’ll get along well.

Mail, Calendar, Contacts

• Mail is an IMAP webclient — Nextcloud is not a mailserver. You still need a server (Microsoft Exchange migration to Mailcow or another self-hosted stack).
• Calendar / Contacts work via CalDAV/CardDAV — sync with Thunderbird, iOS, Android, macOS is seamless. Sharing inside the Nextcloud instance and federation between instances.

Deck, Forms, Tables

These three “productivity apps” are solid:

• Deck: Kanban with cards, lists, labels, assignment, comments. Functionally comparable to Trello or Microsoft Planner. Sufficient for lightweight project planning; for complex roadmaps with dependencies and Gantt, go to OpenProject or commercial tools.
• Forms: Online forms with multiple choice, Likert scales, file upload. Comparable to Microsoft Forms or Google Forms.
• Tables: Structured data in table form for teams — somewhere between Excel and Airtable. Useful for inventory lists, contact directories, lightweight CRM functions.

Installation and architecture

Nextcloud installs in several ways — the SMB recommendation:

Variant 1: Nextcloud AIO (All-In-One) in Docker

• Container stack with Apache, MariaDB, Redis, Collabora, Talk, backup
• Maintenance via Docker update workflow
• Recommended variant for sites with < 100 users
• Runs well on a Proxmox VM with 4 vCPU, 8 GB RAM, storage from TrueNAS

Variant 2: Classic LAMP installation

• Debian/Ubuntu server with Apache/Nginx, PHP 8.3, MariaDB, Redis
• More control, more maintenance work
• Recommended for > 100 users or special requirements (high availability, multi-server setup)

Variant 3: Kubernetes Helm charts

• For several thousand users and HA
• Usually oversized in SMB context

Integration with TrueNAS as storage backend

One of the most frequent DATAZONE constellations: Nextcloud runs as a Proxmox VM or LXC container, primary storage lives on TrueNAS:

Storage connection options:

1. NFS mount from TrueNAS into the Nextcloud VM for the data directory

   • Simple, performant for SMB workloads
   • Nextcloud quotas and permissions apply
   • Backup via TrueNAS snapshots (snapshot best practices)

2. External Storage apps — Nextcloud can mount SMB shares from TrueNAS as additional folders

   • Existing file structures remain usable
   • User quota and permission management stays with TrueNAS

3. S3 backend — TrueNAS offers S3-compatible object storage; Nextcloud can use S3 as primary storage

   • Useful for very large setups
   • More complex backup strategy required

For most SMB setups, variant 1 (NFS for data/) is the most pragmatic — quick to set up, easy to back up, performant up to roughly 200 active users.

Active Directory / LDAP integration

Nextcloud supports LDAP/AD integration out of the box. If you already run an AD or a Samba AD-DC, Nextcloud logins can marry into it:

• Single sign-on via Kerberos or SAML/OIDC (e.g. with Authentik)
• User/group provisioning from AD
• Automatic permission mapping onto Nextcloud shares

For mid-market companies with an existing Windows AD, this is often the natural choice — staff keep their domain password, off-boarding is centralised.

Mobile and desktop clients

• Desktop: sync client for Windows, macOS, Linux — similar to OneDrive
• iOS / Android: apps for Files, Talk, Mail, Calendar
• Outlook plugin: calendar sync with Outlook (alternative: CalDAV with Outlook CalDAV Synchronizer)

Sync client is robust; mobile apps are functional but less polished than commercial counterparts.

Licence and enterprise support

Nextcloud is AGPLv3 (open source). Self-hosting is free. Nextcloud GmbH offers three enterprise subscription tiers:

• Basic — standard support, patches, security advisories
• Standard — higher SLAs, phone support
• Premium — dedicated support manager, customisation support

Prices: list prices per user/year — see nextcloud.com/pricing. Order of magnitude: well below comparable M365 packages.

When does subscription pay off? For productive use with > 50 users in an organisation that depends on guaranteed support. For pure self-service setups without business risk, the community variant plus DATAZONE managed support often suffices.

Realistic limits

We at DATAZONE recommend Nextcloud Hub as an M365 alternative — but honestly:

• UI less polished than M365 in many modules (Talk, mail client). Functionally comparable, but the “fun-to-use” feeling differs.
• Collabora office compatibility not 1:1 with Microsoft Office. Complex DOCX/XLSX documents need case-by-case testing.
• Teams replacement only partial — Talk covers chat and video well, but not the entire Teams ecosystem (Teams channels with files, wiki, app integration, Power Apps).
• Mobile apps are functional but less smooth than Microsoft apps.
• Performance depends directly on server sizing — undersized, Nextcloud runs sluggish.

If you want a sovereign, on-prem productivity setup despite these tradeoffs, Nextcloud Hub is by far the most complete solution on the market.

DATAZONE recommendation

Recommended architecture for an SMB with 50–250 users:

1. Proxmox cluster with 3 nodes (see 3-node cluster with TrueNAS H20)
2. TrueNAS as storage backend (R-Series or H-Series depending on data volume)
3. Nextcloud VM with Docker AIO or classic LAMP — storage via NFS on TrueNAS
4. Authentik or Keycloak as SSO provider, if no AD exists (Authentik article)
5. Mailcow as mailserver backend (Mailcow article)
6. Caddy or Nginx as reverse proxy with Let’s Encrypt certificates (Caddy article)
7. PBS for backup of the entire stack
8. 3-2-1 backup strategy with air-gap component (tape out)

That is a proven setup. We help with migration planning (M365 data export, mail migration, training concept), initial installation and ongoing operations. More under our self-hosting consulting.

Sources and further reading

• Nextcloud — official documentation
• Self-hosting vs. Microsoft 365
• VMware licence costs 2026 for SMBs
• Mailcow mailserver for SMBs
• Authentik Single Sign-On
• Caddy reverse proxy with Let’s Encrypt
• Proxmox 3-node cluster with TrueNAS
• TrueNAS for SMBs
• NIS2 obligations for the mid-market