Real LibreOffice document engineering in the browser: Collabora Online is built by the company employing much of the former SUSE LibreOffice team - not a reimplementation. This deployment runs CODE (Collabora Online Development Edition), the collabora/code server that renders and edits documents entirely server-side while browsers get high-fidelity WYSIWYG output, so layout and formatting survive round-trips that break lesser converters. Four editors ship in one container: Writer for text documents (comments, track changes with comparison and restoration, form handling), Calc for spreadsheets (advanced formulas, macros, pivot tables, per-user sheet views, server-enforced cell protection), Impress for presentations, and Draw for Visio-class diagrams. Format compatibility spans DOCX, XLSX, PPTX, the ODF family, PDF, and dozens more - including Visio and Publisher import. Real-time collaborative editing supports multiple simultaneous editors with visible cursors and commenting. The architectural point: documents are processed on your server and never leave it, which is why Collabora is the engine behind Nextcloud Office and integrates with ownCloud, Seafile, and any WOPI-speaking host - or embeds in your own application via the SDK. An admin console monitors sessions and memory. For organizations that need Google Docs-style collaboration with actual data sovereignty, this is the reference open-source answer.

With 6,800 GitHub stars and over a decade of development since its 2014 release, ONLYOFFICE Docs delivers a self-hosted Microsoft Office replacement with pixel-perfect OOXML rendering and real-time collaborative editing supporting both Fast (character-by-character) and Strict (manual save) co-authoring modes. The suite encompasses five full-featured editors — Document Editor for DOCX/ODT/EPUB/HTML, Spreadsheet Editor with 500+ functions and pivot tables, Presentation Editor with animations and transitions, Form Creator for fillable PDF forms with field validation, and PDF Editor for annotation and conversion — all operating within a unified web interface. Format support spans 50+ types including DOCX, XLSX, PPTX, ODT, ODS, ODP, PDF, CSV, RTF, TXT, and Markdown with server-side conversion between any supported pair. The JavaScript plugin API enables extending editor functionality through a marketplace of ready-made plugins for ChatGPT integration, speech-to-text, OCR, Zotero citations, and Thesaurus. Ready-to-use connectors integrate with Nextcloud, ownCloud, Seafile, Moodle, Odoo, Confluence, SharePoint, Alfresco, Liferay, and Chamilo, while WOPI protocol compliance enables integration with any WOPI-compatible platform. JWT authentication secures all API communications between host applications and the document server. Deploy via Docker with a single command or DEB/RPM packages on Ubuntu, Debian, CentOS, or RHEL. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. GNU AGPL v3 licensed.