Open365: open source Office 365 alternative

Martin Brinkmann
Apr 25, 2016
Updated • May 22, 2018

Open365 is an open source Office 365 alternative that allows you to edit or create documents online, and to sync files with the cloud.

The service is in beta currently but you can sign up for it already on the official website. You may use it using a web browser, download clients for Windows, Mac or Linux desktop machines, or for Android. An iOS client is in the making currently and will be made available as well soon.

Open 365 offers two main features that you can make use of. First, it enables you to synchronize files between devices you use and the cloud.

Second, it allows you to view, edit and create documents in the cloud using the technology provided by the Open Source Office suite LibreOffice Online for that.


You can sign up for the service on the official website currently but the makers plan to release repositories that you can install on servers you have control over to create a self-hosted version of Open365 that you have more control over.

When you sign up for the service you get an email address automatically assigned to you that you use to sign in to the web service and the sync clients, and for mail.

You do get 20 Gigabyte of storage as well right now which is more than what many other file synchronization services offer at the time of writing.

It is unclear however if the 20 Gigabyte are only available during the beta period.

The web service loads the "Hub" view on start automatically. It lists all libraries that you own and that are shared with you by default.

A click on a folder opens the contents directly on the web, a click on files either in one of the editors if the file format is supported, or offered for download if it is not.

The focus is on documents but support goes beyond typical document formats such as docx, xls or pptx. Open365 supports an image viewer that supports all common image formats, and a media player to play audio and video content.

Libraries or individual files can be shared or deleted online, and you may upload new files directly to the web interface using your web browser of choice.

One interesting feature is the ability to create new libraries on the Web, and here specifically the option to encrypt content so that it can only be accessed if the right password is supplied. The password is not linked to the account password.

As far as sharing is concerned, you can share files or libraries with individual users or user groups, and get full control over shared links and permissions online as well.

Document editing and creation

This works for the most part as you would expect it to work. You can load any Office document with a double-click on the web interface, and Open365 will load it in the associated editor.

You can read the document right away there, print it, or start to edit it. If you have used LibreOffice Online or offline before, you will feel right at home, but even if you have not, you will have little issues using Open365 to edit documents.

Open365 saves edits automatically in intervals, but you may use save options to to do manually at any time. Edited documents may be saved online or to the local device instead, and you may export them to the same document format or a different compatible format.

The loading time of documents is a bit slow online right now which means that you will have to wait a couple of seconds before it is displayed in the editor.

Open365 Sync Client

The sync client works for the most part as you would expect it to work. You can use drag and drop to add folders that you want to sync with the cloud, or use the built-in folder browser instead for that.

Folders are turned into libraries automatically when you add them to the sync client. You may change the name of the library and enable encryption before you hit the ok button to start the synchronization.

Options are provided to configure the sync process and other features of the desktop client. You open the options with a right-click on the icon in the system tray.

The settings allow you to set download and upload speed limits, disable http syncing, or configure what the service should do when you remove a library from a local directory or when a library is not found on the server.

Open365 Promo Video

Closing Words

Open365 is an alternative to Office 365 and Google Docs. It is free and open source, and ships both with file sync and document viewing, editing and creation options on the Internet.

The option to install Open365 on your own server may make it interesting to users who want or need to keep full control of documents, and cannot or don't want to use Office 365 or Google Docs because of this.

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  1. Arnie said on September 2, 2016 at 10:46 pm

    Whatever i do. During registration i always get the message “Sorry. We are experiencing some problems”

  2. Jeffrey Johnson said on August 4, 2016 at 11:31 pm

    What does the “Render” and “New Render” tabs do? Can’t figure it out.

  3. Richard said on April 30, 2016 at 5:48 pm

    I was really set to use this, excited even. Then *.deb happened. How disappointing that the rest of the Linux world is excluded.

    Let me know when *.rpm is included.

  4. R said on April 30, 2016 at 5:46 pm

    Only problem is *.deb If I’m not running Ubuntu I get left out. I thought this would be a great alternative but until it supports *.rpm it’s not very useful for me and a lot of the CentOS/Fedora world.

  5. Levins said on April 27, 2016 at 6:44 am

    Longing for an effective Outlook alternative, ideally with full Exchange sync, Gmail,, et al. Mozilla appears to have thrown in the towel with Thunderbird. I understand these are insanely complicated software projects to undertake and commit resources to.

  6. thekreek said on April 27, 2016 at 3:39 am

    Somehow the desktop sync client looks very similar to the SeaFile client….

    1. TheLimeRunner said on May 2, 2016 at 8:32 pm

      That’s because it is! :D

  7. nnn said on April 26, 2016 at 11:57 pm

    What is their outlook equivalent?

  8. Michael said on April 26, 2016 at 10:16 pm

    I will give this a try. I use LibreOffice on my Mac and generally avoid the cloud for sensitive documents because of work requirements and personal privacy concerns. I have been using Zoho for cloud spreadsheets but the performance turned awful two years ago so that I moved some cloud spreadsheets onto my Mac.

    I use iCloud for Notes and Reminders where formatting is very simple and I will likely continue to do that but it would be very nice to be able to read some of my LibreOffice documents on my phone or tablet.

    I currently use Growly Notes on my Mac as my notebook solution (it’s like One-Note with fewer features). Will LibreOffice ever have something like this? I’d be happy to contribute time working on something if there is such a project.

  9. Ian said on April 26, 2016 at 11:06 am

    There are already similar services: OwnCloud has Collaborative Document Editing, RollApp provides full LibreOffice and OpenOffice in the browser, and there has long been ThinkFree Office in the cloud.

  10. John Krazinski said on April 26, 2016 at 1:24 am

    Nice post, Martin.
    Although it is extremely slow rendereing (as if I were accessing a remote computer screen) I think it is very promising.
    I love the idea to use productive tools without having to install it.
    Have a look at,
    Martin, could you write an article gathering online productivity tools and a quick review on them?
    Google docs seems to be abandoned. Still all the same from years ago. Not one new feature that I noticed.

  11. Anonymous said on April 25, 2016 at 8:40 pm

    Source will be opensource very soon.

  12. simone said on April 25, 2016 at 8:10 pm

    Where can I find the source code? How can I do to install it in my server?

  13. Nick said on April 25, 2016 at 6:12 pm

    It says open source, but where can the source code be found? I don’t see any obvious place

  14. neowolf said on April 25, 2016 at 4:36 pm

    You can apply for the beta by just going to the main Web site:

  15. manolito said on April 25, 2016 at 3:35 pm

    The project is not using libreoffice online technology but rather its own, based on the SPICE protocol.

  16. Andreas said on April 25, 2016 at 3:16 pm

    @Jonathan You can register at

  17. Maou said on April 25, 2016 at 2:45 pm

    Nice work Martin, I did not know about this new Open Office, I’m gonna give it a try.
    Btw, they won’t get mad if I sign primarily for that email address ? :)

  18. Jonathan said on April 25, 2016 at 2:44 pm

    I’m not seeing any option for signing up, am I missing something? When I go to all I see is an option to login, nothing that says signup here!

    1. Graham said on April 25, 2016 at 11:49 pm

      Here’s the registration page:

  19. Valrobex said on April 25, 2016 at 2:31 pm

    The lack of true privacy has been the single biggest deterrent for me from using the cloud. And now there’s a cloud office suite that doesn’t include the “telemetric” MS or the snooping, profiling Google… And it runs on Linux!

    As always, fine job Martin, for bringing this to our attention. Will be giving it a try. Thanks.

  20. Dave said on April 25, 2016 at 2:27 pm

    I would point out that there are no decent alternatives to Excel, but then I’d be stuck with basic-level spreadsheet users and open-source fanatics demanding to know why I would say that in some impossibly brief explanation so that they can find faults with the summarized version that they demanded. So I won’t do that. That would be foolish.

    What I could say instead is that basic-level spreadsheet users (and open-source fanatics) have lots of alternatives to Excel. That ought to keep them happy.

    1. ShallowWater said on April 26, 2016 at 7:29 pm

      Not true. I’m not fanatic, but also excel power user (including VBA programming skills). For my job Excel lacks functions that and have. It is point of view. For my duties, nothing is missing, for Dave’s obviously there are some…

      People like Dave give wrong understanding to others and worst they give ready excuse for others not to try alternatives. Sure, he’s not as experienced and demonstrates unclear knowledge in basic-level spreadsheets, but is that enough to conclude?!?

      For those that read so far: Lacking =BASE() made me unhappy with Excel and I stopped using it at once. And of course – ugly transformation of the normal menu to button-bar…

    2. Andrew said on April 25, 2016 at 6:25 pm

      Very true, I tried to move to LibreOffice’s Calc for personal things, and sure enough certain functions and whatnot wouldn’t work… Kinda stopped after that.

      1. Rob said on May 2, 2016 at 10:45 am

        Our organisation has dozens of people using LibreOffice Calc having migrated from Excel, no problems. Surprisingly we receive positive feedback from staff joining the organisation.

        The thing that I love about it is how there appears to be full spreadsheet functionality when the data is moved or created in Writer, so you can then create the same charts and make it look very presentable using Writers DTP like document editing capabilities.

        I am not being paid to comment.

      2. Andrew said on April 27, 2016 at 7:50 am

        I wouldn’t doubt that for a bit. It’s a shame those two can’t work great together, especially since Calc was pushing to be a excel replacement.

      3. James said on April 27, 2016 at 3:04 am

        “Very true, I tried to move to LibreOffice’s Calc for personal things, and sure enough certain functions and whatnot wouldn’t work… Kinda stopped after that.”

        That is funny. I recently tried to share some powerful spreadsheets I created with a friend that uses Excel. After a week of research and tweaking we finally came to the conclusion that Excel didn’t support all the basic functions in LibreOffice Calc. He eventually gave up and downloaded LibreOffice.

        Certainly there are some very powerful things that Excel does that are not possible in LibreOffice, but there are also some really basic things that Excel fails at miserably.

    3. Charax said on April 25, 2016 at 5:08 pm

      True, Excel is a powerhouse, with advanced formulae and functions and VBA, theres really no professional alternative, Excel is great.

      Excel ONLINE however, is a pile of arse, no image support, no support for .xls files(!!!), very little macro support, Excel Online compared to Excel is like a picture of a sports car Vs the car itself.

      Very excited by Open365, will be even moreso when I can install it on my own server

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