Three people open the same file and start typing at once — no copies, no email attachments, no version chaos. Here is what is actually happening under the surface, the two editing modes you can choose between, and the limits worth knowing before your whole office piles in.
Co-editing is the feature that makes a self-hosted office feel like the big cloud suites: several people in one document, seeing each other's cursors live. In the OnlyOffice and Nextcloud combination it works in a specific way that is worth understanding — because every editor's browser connects to the Document Server, while Nextcloud quietly handles the file itself. Once that picture is clear, the modes, the comments and the scaling limits all make sense.
When five people open one document, Nextcloud serves the file once to the Document Server, and all five browsers open their editor session against the Document Server. Every keystroke travels to the Document Server, which keeps everyone's view in sync and only returns the finished document to Nextcloud when the last editor closes it and the final save completes. Practical consequence: the Document Server's address must be reachable from every editor's browser, and the Document Server carries the load of every live session — which is why the planning guide insists on honest RAM.
Fast mode is the default experience most people picture: changes appear on everyone's screen as they are typed, coloured cursors show who is where, and the document saves automatically in the background. It is the right mode for a team drafting together. The honest trade-off is that you see half-finished sentences appear live — some teams love that energy, some find it noisy, and both reactions are legitimate.
In Strict mode, your edits stay invisible to others until you press Save; the paragraph you are working on is locked for you in the meantime. Other users see your finished changes in one clean step instead of watching you think. Offices that prepare formal documents — quotations, letters, reports — often prefer Strict because colleagues review results, not typing. The mode is an OnlyOffice setting you can choose in the connector's advanced configuration; pick per team habit, not per technology.
Collaboration is more than simultaneous typing. Editors can leave comments on selected text, reply inside them, and mark them resolved — the review conversation stays inside the document instead of scattering across chat. Meanwhile Nextcloud keeps its own version history of the file, so if a heavy group edit goes wrong, an earlier version of the whole document can be restored from the Files app. Live editing handles the present; version history is your safety net for the past.
Now the part sales pages whisper: the free Community Edition is built for small teams, and it has a ceiling on how many documents can be open for editing at the same time. The exact number has changed between versions — older releases talked about roughly twenty simultaneous connections, and newer licensing pages phrase the limits differently — so we will not print a number here as gospel. What matters practically: a family or a small office will likely never notice the ceiling, while a whole company editing at 10 AM on a Monday can meet it. If your team is growing towards that point, check the limit stated for your version on the official OnlyOffice site and treat it as a planning signal for the paid editions, not as a failure of the free one.
If cursors lag, look in the right order: the Document Server's available RAM first, then the network path between users and the Document Server, then giant documents with heavy images. Co-editing slowness is almost never a Nextcloud problem, because Nextcloud is barely involved once the session starts. That division of labour is the whole architecture — and knowing it turns a vague complaint into a five-minute diagnosis.
The full OnlyOffice Document Server install and Nextcloud integration, shown live step by step.
▶️ Watch Full VideoIn Fast mode, everyone's changes appear live as they type. In Strict mode, your edits stay private until you save, and the section you are editing is locked for you meanwhile. Fast suits drafting together; Strict suits formal documents where colleagues should see finished changes.
No — every editor's browser connects to the OnlyOffice Document Server, which synchronises the session and returns the saved file to Nextcloud at the end. That is why the Document Server needs the resources and the reachable address.
The free Community Edition has a ceiling on simultaneous editing connections that has varied between versions, historically in the region of a small team's worth of users. Check the exact limit for your version on the official OnlyOffice site — small teams rarely reach it, large offices should plan with it in mind.