Euro-Office or Collabora?

Nextcloud lets you choose between two online office suites. They do the same kind of work in different ways. Below are the differences you can check for yourself; which one is better depends on your situation.

Side by side

Property	Euro-Office	Collabora Online
Based on	A continuation of ONLYOFFICE	LibreOffice technology
Made by	A group of European companies, including IONOS and Nextcloud; no formal governance yet	Collabora Productivity Ltd (United Kingdom)
Licence	AGPL-3.0	Mainly MPL-2.0
Where the work happens	In the user's browser; the server handles co-editing and conversion	On the server; the browser receives the rendered view
Native file format	Microsoft formats (docx, xlsx, pptx). OpenDocument only once enabled, with possible loss when saving	OpenDocument (odt, ods, odp). New files default to OpenDocument; Microsoft formats can be set
Free to use	Yes, in production too: the signed Nextcloud Office build and the Euro-Office community build	CODE, according to Collabora for testing, home use and small teams and not for production. For production: Collabora Online with a subscription
Paid support	Through a Nextcloud Enterprise subscription	Through Collabora and partners, or through a Nextcloud Enterprise subscription
Desktop app	Windows, macOS (Apple silicon), Linux	Windows, macOS, Linux (Collabora Office)
Mobile app	Not yet	iOS and Android (Collabora Office)
In Nextcloud	App ‘Nextcloud Office’ (eurooffice); the default according to the Nextcloud manual	App ‘Nextcloud Office (Collabora)’ (richdocuments); a fully supported alternative according to the manual
Across servers	Co-editing with other Nextclouds that also use Euro-Office. Note: integration 11.0.6 does not open federated files; a fix is waiting (PR #232)	Co-editing with other Nextclouds that also use Collabora, with trusted servers and an extra setting

What to look at

File format. If your organisation mostly works with Word, Excel and PowerPoint files, those are Euro-Office's native formats. If OpenDocument is your standard, that is Collabora's native format.
Server and devices. With Euro-Office the user's computer does most of the processing, with Collabora the server does. Take that into account when sizing your servers.
Phones. Only Collabora has iOS and Android apps today.
Both, per group. Both integrations can live in one Nextcloud, each limited to its own groups; in our test each group got its own editor. If someone has a file open in Collabora, a Euro-Office user gets it read-only: nothing is overwritten, but you do not co-edit either. On public links it is not always predictable which editor opens. Test it first.

Switching from Collabora to Euro-Office

There is no official guide for this switch. The ‘Migration from Collabora Online’ page in the Nextcloud manual is about upgrading Collabora itself. This is what you need to know according to the documentation of both integrations.

The other way round, from Euro-Office to Collabora, broadly the same applies: files stay put, templates are set up again and new files default to OpenDocument.

Files stay where they are. Both editors work on the files in Nextcloud; there is no data migration. Shares, versions and comments belong to Nextcloud, not to the editor.
Take stock of your OpenDocument files. Euro-Office only edits odt, ods and odp once the administrator enables it, and warns that something may be lost when saving. The alternative is converting to docx, xlsx or pptx; the original is kept.
Set up templates again. Collabora's shared templates do not carry over: each integration has its own template folder. OpenDocument templates (such as .ott) cannot be used directly.
New files become Microsoft formats. Euro-Office creates docx, xlsx and pptx by default, where Collabora creates OpenDocument. Tell users beforehand.
Start with one group. Nextcloud's general ‘enable only for groups’ setting does not work for these apps, but each integration has its own group setting. That way one group keeps Collabora while another already uses Euro-Office. Mind files shared between those groups: in two different editors you do not co-edit.
Both enabled at once? Test it. Check per file type which editor opens, including through public links: a reported bug makes a docx open in Collabora there.
Federation. Sharing files with other Nextclouds keeps working: Nextcloud handles that itself. Co-editing across servers only works when both sides use the same editor. Not between a Collabora server and a Euro-Office server: in our test the Collabora side could not open a file from the Euro-Office server at all, and the Euro-Office side opened a Collabora file in its own, separate session. The latter only with the fix from PR #232; the released integration 11.0.6 does not open federated files yet.
Switch in a maintenance window. What happens to documents open during the switch is not documented anywhere.

Sources