Office 365 vs Collabora vs Proton Suite

This is the comparison a growing number of European organisations are typing into Google, and most answers to it are written by one of the vendors. This one is not. The three options are not three versions of the same product. They are three different answers to the question of who your documents answer to, and they are at three different stages of readiness.

See it for yourself: one file, three suites

The fear underneath every migration conversation is that documents will break on the way out. So here is the same board paper, the same .docx file, opened in each suite. No conversion step, no export dance, no reformatting afternoon.

The same everyday tasks

What matters is not the feature list on a vendor page but the things people actually do every week. Here is how the three suites handle them.

Worried about leaving Word and Outlook?

That worry is the single biggest reason organisations stay, and it deserves a straight answer rather than a sales pitch.

Your files are not going anywhere

A .docx written in 2004 opens in Collabora today. The OOXML formats are an open standard, not Microsoft property, and both alternatives read and write them. Migration does not mean converting an archive; the archive simply carries on working.

The ribbon is not the product

Word feels irreplaceable because it is familiar, not because it is uniquely capable. The daily reality of most documents is headings, tables, tracked changes and comments, and all of that sits where you expect it in Collabora. What people genuinely miss is macros and niche add-ins, which is a real but much smaller problem, and one a pilot maps precisely.

Outlook is a habit, not a dependency

Email is built on open protocols, which makes it one of the most portable services you run. Proton Mail imports existing mailboxes and calendars, supports your own domain, and its zero-access encryption means the provider cannot read stored mail at all. And if the timing is wrong, email can move last: documents, storage and video can leave first while Exchange runs out its renewal.

Leaving is reversible

Because your files stay in open formats and your data sits on infrastructure you choose, going back is always possible. That reversibility is what makes a pilot safe: you are not burning the boats, you are checking whether you still need the ferry. Most organisations that pilot properly do not go back, but the option is what makes the first step easy to take.

Side by side, attribute by attribute

Indicative published list pricing, 2026. The calculator is the canonical source for cost arithmetic on this site.

How to choose

If the question is compatibility with a decade of Excel models, Microsoft is still the honest answer, and the exercise becomes about reducing what else you buy from the bundle. If the question is what can replace it this quarter, Collabora on infrastructure you choose is the instant replacement: the files, the keys and the jurisdiction become yours, at roughly a fifth of the per-seat price. If the question is confidentiality, Proton Suite is the only option of the three where the provider reading your board papers is not a policy promise but a technical impossibility, and it is close enough to complete now that the gap is a roadmap item rather than a deal-breaker for most teams.

You do not have to pick one

Bundles train you to think in all-or-nothing terms, and that thinking protects the incumbent. A phased approach works better in practice: Collabora and a European stack as the default documents layer, Proton for the people and papers that genuinely need zero-access encryption, and Proton Meet replacing Teams or Zoom calls. The Microsoft tenancy shrinks to whatever genuinely cannot move, and the renewal negotiation changes character entirely once leaving is credible.

What it costs

For a 50-seat organisation the documents line alone compares roughly €7,500 a year for Microsoft 365 Business Standard with about €1,500 to €1,800 for supported Collabora, before counting the storage, email and video components you may no longer need to buy twice. The savings calculator runs the same published figures against your own seat count.

Further reading

• The sovereign solution: Proton Suite — the Swiss option examined in depth.
• The case for European digital sovereignty — the dependency argument behind every page on this site.
• Residency is not sovereignty — why an EU region of a US cloud changes geography, not jurisdiction.

Questions organisations actually ask

What happens to our 20 years of Word documents?

Nothing dramatic, and that is the point. Collabora is built on LibreOffice and opens .docx, .xlsx and .pptx files natively, including documents written in the last century. They open, they edit, they save back to the same format, and your correspondents never know anything changed. A pilot phase round-trips a sample of your real files so any oddities surface there, not in front of the board.

Will people cope without the Microsoft ribbon?

Yes, faster than expected. Collabora's interface is deliberately familiar: formatting, styles, track changes, comments and tables sit where a Word user expects them. The uncomfortable truth about the ribbon is that most people use a small fraction of it, and that fraction is present and correct in both alternatives. The features people genuinely miss are macros and specialist add-ins, and a pilot identifies exactly who those people are.

Can we keep Outlook and still move everything else?

You can, and many organisations do exactly that as a first phase. Documents, storage and video move to Collabora, Nextcloud and Proton Meet while Exchange stays put for a renewal cycle. When email does move, Proton Mail imports existing mailboxes and calendars, and standard protocols mean a mixed estate works during the transition. Email feels like the scariest piece because everyone uses it every day; in practice it is one of the most portable.

Is Proton Suite really a full Office 365 replacement?

Nearly, and the gap is narrowing release by release. Docs and Sheets now sit alongside Mail, Calendar, Drive and Meet, covering documents, spreadsheets, email, calendar, storage and video with end-to-end encryption throughout. The remaining gaps are a presentation tool, deep spreadsheet features such as pivot tables and macros, and third-party integrations. For sensitive internal work it is already the strongest option on this page; for a heavy Excel estate, not yet.

Which of the three is cheapest?

On indicative published list pricing, per user per year: Microsoft 365 Business Standard runs about €150. Collabora Online is free as a community edition, with supported Business subscriptions from around €36. Proton has a usable free tier, with business bundles from around €84. The savings calculator runs the arithmetic against your own seat count.

Do we have to pick just one?

No, and many organisations should not. A common pattern is Collabora Online on Nextcloud as the default documents layer, Proton for the board, HR and anything genuinely sensitive, and a shrinking Microsoft tenancy kept only for the workflows that genuinely need it. Each piece can be adopted on its own timetable, which is something a bundle never lets you do.

Which is actually GDPR compliant?

The software is half of the answer; where it runs is the other half. Self-hosted Collabora sits under whatever jurisdiction you choose. Proton sits under Swiss law with zero-access encryption, so the provider cannot read your content at all. Microsoft 365 keeps your data inside a US legal regime regardless of which region hosts it, as Microsoft's French Senate testimony in 2025 made plain. Residency in an EU region of a US cloud changes the geography, not the jurisdiction.