Open-source Microsoft 365 alternatives

CryptPad is an open-source collaboration suite with end-to-end encryption. Documents are synchronized between collaborators in real time, and because user data is encrypted, an attacker who breaches the server cannot read the stored content. Administrators who run unmodified code and the service itself also cannot see what users store.

The encryption happens in the browser before data is sent to the server or to collaborators. The README is candid about a limit of this model: the code that does the encrypting is delivered by the host server, as on any website, so users must trust the administrator to keep the server secure. Repository topics mention collaborative editing, real-time work and the ChainPad algorithm.

CryptPad is written in JavaScript and licensed under AGPL-3.0. A developer guide covers setting up a local instance, and an admin guide covers production deployments. Official Docker images for AMD64 and ARM64 are published with every release, and a Dockerfile and docker-compose.yml are included in the repository.

LibreOffice is a free office suite whose licenses are copyleft, built to open and save most common document formats and standards. It is free to download, use and distribute, and it is backed by The Document Foundation, which represents an independent community of enterprises, developers and other volunteers.

This GitHub repository is a read-only mirror of the core code: pull requests are not accepted, contributions go through Gerrit, and downloading a zip is discouraged in favor of the project's source bundles. Developers can add features by working on the code base in C++, or write extensions using the SDK and UNO APIs, which are also used by macro scripting in StarBasic.

The README documents the minimum build and runtime baselines for Windows, macOS and Linux, plus iOS for LibreOfficeKit and Android builds. As is widely known, the suite includes applications for word processing, spreadsheets, presentations, drawing and databases. Its code is written mostly in C++.

Collabora Online is an open-source, web-based office suite built on LibreOffice technology. It lets users open and edit documents in the browser, and the project's topics also reference mobile apps for iOS and Android. It is aimed at organizations that want document editing they can control, often integrated into other collaboration or file-sharing platforms.

This GitHub repository has a narrower role than the product as a whole. Active development and code review have moved to the project's own Gerrit instance, and the GitHub repository is kept for issue tracking and for release artifacts, including the nightly container image, the Helm chart and build assets. Pull requests are welcome only for the Helm chart and the Docker image build, and a read-only source mirror is available elsewhere.

Because the container image and Helm chart are published from here, the software is designed to be deployed on your own infrastructure, including Kubernetes. The code is a mix of C++, JavaScript and shell scripts. Contributors should follow the contributing guide and push source changes to Gerrit rather than GitHub.

ONLYOFFICE Docs, published in this repository as the document server, is an online office suite that bundles viewers and editors for text documents, spreadsheets, presentations, forms and PDF files. It is built around Office Open XML formats such as docx, xlsx and pptx, and it supports collaborative editing in real time. The server component runs on Node.js and is licensed under AGPL-3.0.

The vendor's site describes several ways to use it. Docs can be connected to other platforms for in-place editing, with ready integrations for products such as Box, Moodle, Nextcloud, Odoo and WordPress. It can be embedded in your own service under your own brand, and it powers the vendor's DocSpace, where you create rooms and invite people to work on documents. A demo lets you try editing and form filling without registration.

Free desktop apps for Windows, Linux and macOS and mobile apps for iOS and Android are offered for working with documents offline or on the go. The site also offers templates for forms, text documents, spreadsheets and presentations, and converters between formats. Commercial plans and pricing are published by the vendor.

ONLYOFFICE Groups, formerly known as Community Server, is an open-source collaborative platform that serves as a central workspace for a team. It brings documents, projects, customers and email together in one place, and from version 11.0 it is distributed under the Apache 2.0 licence.

Document management covers file sharing with flexible permissions, links to cloud storage such as Google Drive, Box, Dropbox, OneDrive and ownCloud, and embedding of documents in websites. Project management offers milestones, tasks and subtasks, Gantt charts, time tracking and automated reports. The CRM stores contacts and interactions, generates invoices, tracks payments and offers web-to-lead forms.

Collaboration tools add blogs, forums, an internal wiki, a shared calendar, a mail client that aggregates several accounts, and an employee directory. It forms the base of the wider ONLYOFFICE Workspace suite, which can be extended with ONLYOFFICE Docs for document, spreadsheet, presentation and PDF editing, a mail server, Talk messaging and a control panel. The code base is C#.