Best Open Source Office Suites from Europe (2026)

An open source office suite is word processing, spreadsheet and presentation software whose source code is published under a licence that lets anyone inspect, run and modify it, so the buyer can check what the software does and keep using it without a vendor's permission.

How we rank these tools — 4-step process

1
European ownership, verified
The company is headquartered and incorporated in the EU, EEA, the UK, Switzerland or Israel, and processes customer data in Europe or Israel. A US parent company disqualifies a tool from this page regardless of where its servers are.
2
Category fit and hands-on review
What the tool actually does, who it suits, and where it falls short — checked against the vendor’s own documentation, changelog and pricing page rather than its marketing copy.
3
Compliance and pricing check
GDPR posture, hosting location and the prices quoted on this page are verified against the vendor’s public pricing before publication, and re-checked when we revisit the category.
4
Position on this page
Placement on this page can be paid, and that can affect the order tools appear in. It never buys a listing: a tool that fails the checks above is not here at any price, and payment does not change the shortcomings we write about. A vendor can ask us to correct a factual error — not to remove a criticism.

Vendors can pay for visibility on this page. It never changes what an entry says about a product, including the criticism, and we earn nothing when you click through to a vendor. Vendors can pay for more visibility, higher up on the review pages; it never affects whether a tool is listed. Editorial policy

Editor Sebastiaan Smits

Published 13 November 2026 Last reviewed 13 November 2026 How we review

Key takeaways

LibreOffice, developed by The Document Foundation in Berlin, is free, runs entirely on your own machine and is licensed under MPL 2.0 and LGPL.
OnlyOffice (Ascensio System SIA, Riga) is licensed under AGPL 3.0 and offers a free self-hosted Community Edition for up to 20 concurrent connections.
Collabora Online, from Collabora Productivity Ltd in Cambridge, is open source under MPL 2.0 and builds on LibreOffice technology.
Nextcloud GmbH in Stuttgart releases Nextcloud under the AGPL, while ownCloud's Infinite Scale core is Apache 2.0 licensed with an unlimited-user Community Edition.
CryptPad (XWiki SAS, Paris) combines open source code with zero-knowledge encryption and a hosted free tier of 50MB.

Open source matters in an office suite for a practical reason: documents outlive vendors.

This ranking covers eight European projects whose own tool pages state an open source licence or open code, and orders them by how complete the licence terms are and how much of a working office suite you get at no licence cost. Seven are open source in the full sense; Proton Docs is included on the strength of its published client code and is marked as such.

8 European office suites compared

European office suites compared on position, country, entry price and best use
Position	Tool	Established	Entry price	Best for
#1	LibreOffice	Germany	Free and open source	A complete free suite that works offline without an account
#2	OnlyOffice	Latvia	Free desktop and self-hosted Community / DocSpace Business $20 per admin per month	Open source editing that keeps Microsoft layouts intact
#3	Collabora Online	United Kingdom	Free Community Edition / Enterprise on request	Browser-based collaborative editing on infrastructure you control
#4	Nextcloud	Germany	Free (self-hosted) / enterprise plans available	Documents, files, calendar and calls in one self-hosted workspace
#5	CryptPad	France	Free (50MB) / from about €5/month (5GB)	Open source collaborative editing where the server cannot read the content
#6	ownCloud	Germany	Community Edition free, self-hosted, unlimited users, 100% open source / Enterprise and Standard from 25 users, annual commitment, quote-based / ownCloud.online hosted plans from 1 user, quote-based / volume and education licensing on request, from about €1.85/user/year	A self-hosted file platform with an editor of your choice
#7	Calligra Suite	Germany	Free and open source	Linux desktops that want a native, community-built suite
#8	Proton Docs	Switzerland	Free with any Proton account, including the free plan; higher storage and collaboration limits come with the paid Mail Plus, Drive Plus, Proton Unlimited and Proton Business plans — exact rates on proton.me/pricing depend on currency and billing cycle	Encrypted documents and spreadsheets inside a Proton account

The 8 tools reviewed

#1 LibreOffice

Berlin, Germany Founded 2010 Free and open source Free

Best for: A complete free suite that works offline without an account

Operating company. The Document Foundation
Jurisdiction. EU (Germany), non-profit foundation
Where the data sits. Runs entirely on your own machine
Independent checks. GDPR (no data leaves the device)
Source code. Open source
Replaces. Microsoft 365, Google Docs

LibreOffice bundles Writer, Calc, Impress, Draw, Base and Math under MPL 2.0 and LGPL, and it is developed by The Document Foundation, a non-profit in Berlin. It installs locally, needs no account and sends nothing anywhere, so the open source question and the data question have the same short answer.

ODF is the native format, and Microsoft formats are read and written well enough for ordinary exchange. A heavily formatted DOCX can still shift between LibreOffice and Word, and real-time co-editing needs Collabora Online on top. Because the foundation sells nothing, there is no paid tier to move up to.

What LibreOffice does well

Six applications under permissive-weak copyleft licences
No account, no cloud, no telemetry path
Non-profit steward with no licence sales

Where LibreOffice falls short

Complex DOCX layouts can shift
No built-in real-time collaboration

Standout feature. It is the reference implementation that the other open source editors in this list derive from or integrate with.

Read the full LibreOffice review Visit LibreOffice

#2 OnlyOffice

Riga, Latvia Founded 2009 Free desktop and self-hosted Community / DocSpace Business $20 per admin per month Free desktop editors

Best for: Open source editing that keeps Microsoft layouts intact

Operating company. Ascensio System SIA
Jurisdiction. EU (Latvia)
Where the data sits. EU, or self-hosted
Independent checks. Open source
Source code. Open source
Replaces. Microsoft 365, Google Docs

OnlyOffice is published by Ascensio System SIA in Riga under AGPL 3.0. It is built around the DOCX, XLSX and PPTX formats, which makes it the open source option with the closest match to Microsoft layouts. Free Desktop Editors run offline on Windows, macOS and Linux for personal and commercial use.

The free self-hosted Community Edition is limited to 20 concurrent connections, and the DocSpace cloud costs $20 per admin per month according to the tool page. Beyond 20 connections a paid edition is needed, so the open source licence does not mean unlimited free hosting. OnlyOffice embeds into Nextcloud, ownCloud, Seafile, Alfresco, SharePoint and Confluence.

What OnlyOffice does well

AGPL 3.0 code with free desktop editors
Strongest Microsoft format handling of the open source group
Embeds into several file platforms

Where OnlyOffice falls short

Community Edition capped at 20 connections
No end-to-end encryption

Standout feature. The AGPL code and the OOXML-first design come from one company, so format fidelity is not a plug-in.

Read the full OnlyOffice review Visit OnlyOffice

#3 Collabora Online

Cambridge, United Kingdom Founded 2015 Free Community Edition / Enterprise on request Free Community Edition

Best for: Browser-based collaborative editing on infrastructure you control

Operating company. Collabora Productivity Ltd
Jurisdiction. Wherever you host it
Where the data sits. Your own infrastructure, or European managed hosting
Independent checks. Open source (MPL 2.0)
Source code. Open source
Replaces. Google Docs, Microsoft 365

Collabora Online is open source under MPL 2.0 and builds on LibreOffice technology. It is operated by Collabora Productivity Ltd in Cambridge, so the company sits in the UK even though the software runs wherever you host it. A free Community Edition exists, and enterprise support is available on request.

Deployment options include Docker, Kubernetes Helm charts and multi-server high availability, plus native packages for Debian, Ubuntu, CentOS and RHEL. It speaks WOPI, so it connects to Nextcloud, ownCloud, Seafile and other compatible storage. OOXML rendering is good but less exact than OnlyOffice, and the buyer owns uptime, updates and backups.

What Collabora Online does well

MPL 2.0 licence and free Community Edition
WOPI works with any compatible storage
Docker, Kubernetes and native packages

Where Collabora Online falls short

OOXML rendering less exact than OnlyOffice
Enterprise pricing is not published

Standout feature. It turns the LibreOffice engine into a browser editor that file platforms can embed.

Read the full Collabora Online review Visit Collabora Online

#4 Nextcloud

Stuttgart, Germany Free (self-hosted) / enterprise plans available Free self-hosted

Best for: Documents, files, calendar and calls in one self-hosted workspace

Operating company. Nextcloud GmbH
Jurisdiction. EU (Germany)
Where the data sits. Self-hosted, or a managed provider you choose
Independent checks. GDPR (depends on hosting)
Source code. Open source
Replaces. Microsoft 365, Google Workspace

Nextcloud GmbH in Stuttgart releases Nextcloud under the AGPL, free to self-host. Nextcloud Office adds collaborative documents, spreadsheets and presentations to the file platform, next to calendar, contacts and Talk, under one login. The office editing itself is Collabora technology.

Enterprise plans and a network of managed European providers exist for organisations that want control without running the server. The open source licence does not settle data protection: GDPR compliance depends on how and where it is hosted. Performance also needs attention as the installation grows.

What Nextcloud does well

AGPL code, free to self-host
One administration for files, office and calls
Managed European providers available

Where Nextcloud falls short

You run it or pay someone to
Editor fidelity is that of Collabora

Standout feature. It is the only entry that gives a whole workspace, not only an editor, under an open source licence.

Read the full Nextcloud review Visit Nextcloud

#5 CryptPad

Paris, France Founded 2016 Free (50MB) / from about €5/month (5GB) Free tier

Best for: Open source collaborative editing where the server cannot read the content

Operating company. XWiki SAS
Jurisdiction. EU (France)
Where the data sits. France
Independent checks. Open source, zero-knowledge
Source code. Open source
Replaces. Google Docs, Notion

CryptPad is built by XWiki SAS in Paris and is open source, with French hosting. Encryption happens on the client with keys the server never receives, and several people can still edit together. It covers documents, spreadsheets, presentations, kanban boards, forms and a whiteboard.

The tool page states a free tier of 50MB and paid storage from about €5 per month for 5GB, and organisations can self-host. The cost of zero-knowledge is real: very large documents run slower than in a server-side editor, Microsoft format fidelity is not the priority, and a lost key means a lost document.

What CryptPad does well

Open source with zero-knowledge encryption
Wide range of document types
Free 50MB tier, paid from about €5/month

Where CryptPad falls short

Weaker on very large documents
A lost key cannot be recovered

Standout feature. It pairs published code with encryption that is checkable, so privacy does not rest on a policy.

Read the full CryptPad review Visit CryptPad

#6 ownCloud

Regensburg, Germany Founded 2010 Community Edition free, self-hosted, unlimited users, 100% open source / Enterprise and Standard from 25 users, annual commitment, quote-based / ownCloud.online hosted plans from 1 user, quote-based / volume and education licensing on request, from about €1.85/user/year 30-day free trial (Enterprise); 14-day free trial (ownCloud.online)

Best for: A self-hosted file platform with an editor of your choice

Operating company. ownCloud GmbH (acquired by Kiteworks)
Jurisdiction. EU (Germany)
Where the data sits. Germany (ownCloud.online hosting), or self-hosted wherever you choose
Source code. Open source
Replaces. Dropbox Business, Box, Microsoft SharePoint

ownCloud GmbH in Regensburg develops ownCloud, whose Infinite Scale core is Apache 2.0 licensed. The Community Edition is free, self-hosted and unlimited in users. Collabora Online or ONLYOFFICE is embedded for document, spreadsheet and presentation editing from the file manager.

Enterprise and Standard tiers start at 25 users on an annual commitment and are quote-based, while volume and education licensing starts from about €1.85 per user per year according to ownCloud's pricing page. The company is described as acquired by Kiteworks, so a buyer who weighs ownership should read that line. Editing fidelity belongs to the embedded editor, not to ownCloud.

What ownCloud does well

Apache 2.0 core with unlimited-user Community Edition
Choice of Collabora Online or ONLYOFFICE
Hosted option in Germany

Where ownCloud falls short

Fidelity depends on the embedded editor
Enterprise pricing is quote-based

Standout feature. It has the most permissive licence of the platform projects here, Apache 2.0 for the Infinite Scale core.

Read the full ownCloud review Visit ownCloud

#7 Calligra Suite

Berlin, Germany Free and open source Free

Best for: Linux desktops that want a native, community-built suite

Operating company. KDE community (legal body: KDE e.V.)
Jurisdiction. EU (Germany), non-profit association (KDE e.V.)
Where the data sits. Runs entirely on your own machine
Source code. Open source
Replaces. Microsoft Office, LibreOffice

Calligra Suite comes from the KDE community, whose legal body KDE e V is a registered non-profit association in Berlin. Words, Sheets and Stage cover documents, spreadsheets and presentations under LGPL 2+ and GPL, installed locally with nothing transmitted. Version 4.0, released in August 2024, moved the suite to Qt6 and KF6.

The suite is aimed at Linux: the download page says Windows support is still being worked on, and no macOS build is listed. There is no real-time collaboration, no hosted version and no vendor support. Words opens .doc and .docx files and saves to ODF, so exchange with Microsoft users goes through conversion.

What Calligra Suite does well

LGPL 2+ and GPL with no paid tier
Words, Sheets and Stage in one suite
Fully local, no data leaves the device

Where Calligra Suite falls short

Linux-focused, no macOS build listed
No collaboration and no vendor support

Standout feature. It is built by volunteers with no company behind it, so there is no commercial roadmap to depend on.

Read the full Calligra Suite review Visit Calligra Suite

#8 Proton Docs

Geneva, Switzerland Free with any Proton account, including the free plan; higher storage and collaboration limits come with the paid Mail Plus, Drive Plus, Proton Unlimited and Proton Business plans — exact rates on proton.me/pricing depend on currency and billing cycle Free plan includes Proton Docs and Proton Sheets

Best for: Encrypted documents and spreadsheets inside a Proton account

Operating company. Proton AG
Jurisdiction. Switzerland (adequacy decision, outside the EEA)
Where the data sits. Proton's own European data centres (API and database servers)
Source code. Open source
Replaces. Google Docs, Google Sheets, Microsoft 365

Proton Docs, from Proton AG in Geneva, is a real-time collaborative editor inside Proton Drive, with Proton Sheets alongside it. The tool page lists the client code as open source, published in Proton's WebClients repository. The pages read do not state a licence for the server side, so this entry is open source in the client sense only.

Docs and Sheets are included with any Proton account, including the free plan, and run on Proton's own European data centres under Swiss jurisdiction, outside the EEA but covered by an adequacy decision. There is no presentation app, Microsoft fidelity is not the focus, and Sheets is newer than Docs. A team outside the Proton ecosystem adopts an account system, not only an editor.

What Proton Docs does well

Client code published in the WebClients repository
End-to-end encryption with live co-editing
Free with any Proton account

Where Proton Docs falls short

Open source for the client, not stated for the full stack
No presentation app

Standout feature. It is the only entry here with a free tier inside a wider encrypted account, with its client code published.

Read the full Proton Docs review Visit Proton Docs

What does "open source" change for an office suite buyer?

It changes who controls the upgrade path. With published code under a recognised licence, a public body or company can keep running the software, pay another provider to maintain it, or fork it, as ownCloud and Nextcloud show. A closed suite offers none of those routes if the vendor changes terms.

It does not change cost, hosting or data protection by itself. LibreOffice costs nothing and runs locally, but Nextcloud needs a server and an administrator, and the GDPR position of a self-hosted tool depends on where and how it is run.

How do the licences differ in practice?

The entries here fall in three groups. MPL 2.0 and LGPL (LibreOffice, Collabora Online, Calligra) are weak copyleft, AGPL (OnlyOffice, Nextcloud) requires publishing modifications made to a service you offer over a network, and Apache 2.0 (ownCloud's Infinite Scale core) is the most permissive.

For an organisation that only uses the software, the differences rarely bite. They matter if you modify the code, bundle it into a product, or host it for others, so ask legal counsel before doing any of those.

Which open source option handles Microsoft documents best?

OnlyOffice is built around DOCX, XLSX and PPTX and has the closest match to Microsoft layouts of the group. Collabora Online, and therefore Nextcloud Office, is good but slightly behind on complex documents, and LibreOffice and Calligra are ODF-first.

Test with your own five hardest files before standardising: a document with tracked changes, a spreadsheet with macros and a deck with embedded objects. Any entry that fails one of them is a conversion tool in your workflow.

How do I migrate away from Microsoft 365 or Google Workspace?

Start with the file exchange habit, not the software. Decide whether the organisation shares files as DOCX or ODF, then pick an editor to match: OnlyOffice for DOCX, LibreOffice for ODF. A local suite replaces Word, Excel and PowerPoint, but mail, calendar and chat need a separate answer, which is where Nextcloud or ownCloud come in.

Run both systems side by side for a quarter, and move the heaviest co-editing teams last. Expect to spend more time on templates and macros than on the documents themselves.

When should I not choose an open source suite?

When nobody can operate it. A self-hosted Nextcloud or Collabora installation needs updates, backups and monitoring, and a small team without technical staff is better served by a hosted option or by a local suite such as LibreOffice.

Also reconsider if your clients send macro-heavy Excel files or require exact Word layouts, because open source engines approximate those. In that case keep the proprietary tool for client-facing files and use the open source suite internally.

How we selected and ranked these 8 tools

Every tool on this page is in the European Purpose directory, which means the operating company is established in Europe and we have verified that from the company register or the vendor's own legal notice rather than from a marketing page. Tools headquartered outside Europe are not eligible, however good they are.

Feature verification (weight: 40%). We check each capability against the vendor's own documentation and product pages, and record what the tool does rather than what the category is assumed to include.
Ease of adoption (weight: 30%). Integrations, published API access, trial availability and how much configuration stands between signing and a usable result.
Value and transparency (weight: 30%). Published pricing counts in a vendor's favour; quote-only pricing is recorded as quote-only rather than estimated. We weigh what a buyer gets for the entry price, not the headline feature count.
Editorial review. Every page is researched and drafted with AI assistance, and the compliance and pricing claims are checked against the vendor's documentation before it is published under the founder's editorial responsibility. The three weights above decide the order; a position is a ranking against the other European tools in this category, not an absolute score.

Vendor-reported outcomes — ROI figures, margin uplift, time saved — are labelled as vendor claims wherever they appear on this page. We have not audited them, and neither has anyone else who quotes them. Read our full editorial process for how pages are re-verified.

Frequently asked questions

Which open source office suite is completely free?

LibreOffice and Calligra are free with no paid tier. OnlyOffice offers free desktop editors and a free self-hosted edition up to 20 concurrent connections, and ownCloud's Community Edition is free with unlimited users.

Which open source option offers real-time collaboration?

Collabora Online, OnlyOffice, Nextcloud Office, CryptPad and Proton Docs all support simultaneous editing. LibreOffice and Calligra do not have it built in.

Which entries are encrypted end to end?

CryptPad uses zero-knowledge encryption, and Proton Docs is end-to-end encrypted. OnlyOffice states no end-to-end encryption.

Is the company behind each suite European?

Six of the eight are headquartered in the EU (Germany, Latvia and France). Collabora Productivity Ltd is in the UK and Proton AG in Switzerland, both outside the EU, and Collabora Online runs wherever you host it.

Can these suites run on my own server?

OnlyOffice, Collabora Online, Nextcloud, ownCloud and CryptPad can be self-hosted. LibreOffice and Calligra install on a desktop, and Proton Docs is a hosted service.