ONLYOFFICE VS Collabora: a critical comparison

Since our integration with Nextcloud, we are even more frequently asked what exactly does ONLYOFFICE have that our direct competitor, Collabora, doesn’t?

Talking advantages, Collabora does have one significant, ideological, advantage. This product is basically the successor of OpenOffice and LibreOffice’s open source legacy. The battle for users runs tough, however, we have aces up a sleeve, and these are what this story is all about.

A short anatomy lesson

Briefly, Collabora is a visual representation of a server-hosted editor sent to your browser. This editor is called LibreOffice and Collabora is somewhat a thin client: there’s not much going on on your very computer. The whole process runs on the server and is instantly shown within Collabora’s interface, which is visually different from the one you can find in LibreOffice.

In ONLYOFFICE these are resources of a client that we rely on. The editor indeed works right in your browser and constantly exchanges its data with the server. While Collabora delegates nearly everything to the server, we put only a handful of processes there including saving, conversion and spell checking. That greatly saves server resources and keeps work running faster.


It is not hard to grasp how Collabora renders your inputs. The page is split into blocks that allows loading it slightly faster. However, the fact that these pictures travel from the server might get a little interruptive: add a bit of connection instability and get one block rendered slower than others or not rendered at all. No lies, we did do tests.

The construction of Collabora is slow by very nature since the editor is remote from the user: you only see a picture puppeted by the coordinates.

ONLYOFFICE gives you the complete editor in your browser. We process every event on client side and send the results to the server. That seems to deliver a much more rapid editing process than a vice-versa approach.

Functionality: the real and the potential

The heritage of LibreOffice is a true advantage of Collabora. The developers don’t need to invent any feature, everything can be automatically imported from LibreOffice. However, not everything has been: you have no autoshapes or charts, no tables of contents. Although document opening is performed on LibreOffice level, the editing capabilities remain basic for no known reason.

Sometimes we hold, or participate in, events where we present our editors and are asked something like ‘can I change fonts in ONLYOFFICE or switch to bold?’. And we indeed get upset because we have been through this stage long ago and already feature all possible objects, variously customizable diagrams, autoshapes and formulas. We are currently finishing work on tables of contents, pivot tables (already available for opening) and in-built digital signing.

Bad genes: compatibility

Clearly, Collabora inherited every bug and every drawback of LibreOffice. The most significant is a (very) bad compatibility with Microsoft formats.

This is absolutely not a problem if you and every of colleague of yours are worshiping ODF. This is a problem for those who strongly prefer Microsoft or by the will of fate have to work with a mass of documents from multiple sources. These will not make friends with Collabora.

Almost 99% of the known text documents are stored in .DOC or .DOCX. The open and free office suites indeed inspire, but Microsoft remains the world-class champion and has its editors installed everywhere, saving documents in OOXML since 2007.

ONLYOFFICE has its core built on .DOCX, .XLSX and .PPTX because we simply want to seamlessly open majority of the existing documents, not just a few of them. And we will do it much better than Collabora or LibreOffice. This has been our job since the beginning.

Sure, we work with ODF too, converting it, and doing it better and better.

Architecture: is Collabora cheaper?

No, it is not, and mainly because of consuming your server capabilities. This is the very essence of accommodating editors on the server and pigeon-mailing images to the clients.

Let’s take a quick look at this example:

  1. You open a document that costs you 500 MB of your memory (plus possible increased consumption due to conversion processes).
  2. Your colleague opens a document that again takes 500 MB.
  3. Someone opens another document of 700 pages, that takes away another 1.5 GB.
  4. Eventually, you end up with overloaded server, only because three people opened their documents.

Balancing servers helps, you would say. But when you invite a co-worker to edit a report together, they work with an editor hosted by the same server. Ten more people are already editing their documents there and whoops, here come slowdowns and outages.

A dual core server with 2 GB per core would averagely fit a team of eight to ten people. How many would you need? With a bigger team in the office, a suite like this would make you babysit your servers on a permanent basis, balancing and optimizing, still having processes interrupt one another.

Architecture of ONLYOFFICE, optimized before installed

Because we let your servers relax. Again, everything happens on a machine of a person who carelessly opened fifteen documents and is editing five of them simultaneously. Sure enough, the server takes responsibilities, but much less than if it would host an editor.

We keep the client and the server connected, but only to a minor, necessary extent. The practice shows that an average server with ONLYOFFICE running can afford 75 actively edited documents per core. Going back, while a hypothetical dual core machine with Collabora on can serve eight to ten users, ONLYOFFICE can take 150.

Collaborative editing: let’s share the document, not the toolbar

Collabora has launched the co-editing features based on a single editor for all active users working on the document. This implies sharing not only the editing process, but also the editing modes.

Imagine two people co-editing a document in Collabora. If someone switches the Track Changes mode on, it (most often, unexpectedly) launches for every user. We assume this is why Collabora doesn’t feature non-printable characters, for example.

This cannot possibly happen in ONLYOFFICE since an editor is yours faithfully, in your own browser and under your control. You can switch co-editing modes, Track Changes, non-printables, etc. without getting annoying.

What do you expect from the Undo button?

When you hit Ctrl+Z you expect that the last change you made disappears. When you co-edit a document you, too, would rather have your change undone.

In Collabora Undo and Redo relate to the whole document. Let us explain:

  1. User 1 types ‘A’.
  2. User 2 types ‘B’.
  3. User 1 wants to undo ‘A’, but no luck: the last input belongs to User 2.
  4. User 2 needs to cancel their change first. Why would User 2 do it?

Collabora does not differentiate solo editing from collaboration here. The only algorithm is reversing the changes in that very order they have been made.

In this approach there is another tiny wonder happening. Because the Undo button on your toolbar becomes locked when It was not you who made the last change, you can watch it change there and back. Your toolbar is independent from your own actions.

In ONLYOFFICE you can undo changes in any co-editing mode (we have two of them, Strict and Fast). The key here is that everything happens on the client side, including the sequence of the changes. The server is just a database that synchronizes the inputs.

So far:

  • Collabora works with OpenDocument formats way better than ONLYOFFICE does, but is certainly worse at OOXML (.DOCX, .XLSX, .PPTX);
  • The functionality of ONLYOFFICE is broader than one of Collabora at present. However, Collabora potentially has everything LibreOffice does (and it does have a lot);
  • One dual core server can accommodate eight to ten users with Collabora, or 150 with ONLYOFFICE.
  • In Collabora, all actions are processed on the server, while ONLYOFFICE uses client’s resources;
  • Collabora is slower;
  • Co-editing in Collabora runs in the single editor on the server shared by all users in the document and this causes troubles;
  • In ONLYOFFICE everyone has their own editor in the browser. The server is only a database that keeps changes and final file versions.

It is up to you to choose what to use for your team, we are only here to help. However, we insist that Collabora is slow, raw and buggy. This can be changed with better internet connection on your side and future solution improvements from developers. But ONLYOFFICE is already here, at beck and call.