Collabora Online

Collabora Online is an open source online office suite developed by Collabora Productivity, a division of Collabora. It has LibreOffice at its core. The web application allows collaborative editing of text documents, spreadsheets, and presentations.
Features.
Any modern web browser without plug-ins or add-ons can access Collabora Online to edit or collaboratively edit text documents, spreadsheets, presentations and vector graphics.
Collaborative functions include comments which other users can respond to, and document version history enabling comparison of documents and restoring among other things. Advanced collaborative functions include things like integrated video calls or chat whilst collaboratively editing documents, these are possible as Collabora Online integrates with enterprise file synchronisation and sharing cloud solutions such as Nextcloud, ownCloud, Seafile and EGroupware. 
Smartphone, Tablet, Chromebook and Desktop editing.
No client apps are required to access Collabora Online, the online app can be accessed by devices with a modern web browser. Native software apps are available for most devices and operating systems, these apps are called Collabora Office, as with Collabora Online these are all built on the core of LibreOffice.
File Formats.
Collabora Online supports the Open Document Format (odt, odp, ods), the Office Open XML formats (docx, pptx, xlsx) as well as legacy Microsoft Office formats (doc, ppt, xls). Other formats supported include pdf, csv, rtf, and epub. Visio, Publisher, Keynote, Numbers, Pages, and other file formats can be imported.
Server.
Collabora Online allows real time collaboratively editing of text (word processing) documents, spreadsheets, presentations and vector graphics editing. Server/s can be hosted locally or with a provider, privately hosted cloud services allow data to remain under the control of the respective users, Collabora Productivity support Collabora Online server instances for Debian, Ubuntu CentOS, openSUSE, Univention Virtual Machines and Docker images. It is often integrated with file share and collaboration cloud platforms, such as Nextcloud, ownCloud, Seafile and EGroupware, which are functionally similar to Dropbox, Google Drive and Microsoft 365, these typically include email, contacts, calendar, file sync and share, calls, chat and video, with apps stores. Close integrations are possible, enabling things like the possibility to edit documents within a chatroom or a video call, as with Nextcloud's built-in video-conferencing tool Nextcloud Talk. Server integrations can simultaneously exist with several cloud solutions such as Moodle, Alfresco, Kolab, Mattermost, Sharepoint and others. Collaborative functions include comments which other users can respond to, document version history enabling the comparison of documents and their restoration, and other things. Enterprise ARM is supported; However a home server can be made using a Raspberry Pi 4, this can be achieved using a Ubuntu Appliance which includes the Collabora Online office suite.
Technology.
The core of Collabora Online is written in C++ just like the core of LibreOffice. It uses the LibreOfficeKit, a programming interface that allows the reuse of most of the existing LibreOffice code and the saving, loading and rendering of documents. The basic principle of Collabora Online is that documents never leave the server. The parties working on the documents see tile-rendered images of the document and send their changes back to the server. The visible user interface of Collabora Online is written in JavaScript. For file access and authentication with a file hosting services, Collabora Online uses the WOPI protocol developed by Microsoft. This means that Collabora Online can - in theory - be used with any instance allowing a Microsoft 365 integration.
Reviews.
Collabora Online was discussed in various online and print publications. In December 2016 the tech website Softpedia mentioned the availability of collaborative editing in version 2.0 and the integration with Owncloud, Nextcloud and other FSS solutions. The technology website ZDNet reported in June 2020 that Collabora Online from version 19 of Nextcloud will be delivered as a standard office package and that within the native video conferencing software Talk direct editing of documents is now possible. The technology blog OMG! Ubuntu! covered the release of the Android & iOS apps pointing out the possibility to use them in offline mode. In September 2020 Linux Magazine compared Collabora Online with OnlyOffice, mentioning the flexibility and platform independence of both tools and pointing out large set of features Collabora Online draws from LibreOffice.
History.
The former LibreOffice development team from SUSE joined Collabora in September 2013 forming the subsidiary Collabora Productivity. In 2015 Collabora and IceWarp announced the development of an enterprise-ready version of LibreOffice Online to compete with Google Docs and Office 365 (now called Microsoft 365). In December 2015, the company's partnership with ownCloud and release of "CODE" (Collabora Online Development Edition) was announced on Joinup. In October 2020 Collabora announced the move of its work on Collabora Online from The Document Foundation infrastructure to GitHub.