Open-source Google Workspace alternatives

Nextcloud Server is a platform for keeping your files, contacts, calendars and other data on a server of your choosing. Content is synchronized across your devices, can be shared with other people for viewing or collaboration, and stays under your control rather than with a large cloud provider. It grew out of the ownCloud lineage.

Functionality can be expanded through hundreds of apps in its App Store, including Calendar, Contacts, Mail and Video Chat. Security measures include encryption mechanisms, a public bug bounty program and two-factor authentication. There are several ways to get a Nextcloud: sign up with a provider, install the server yourself on your own hardware or with a ready-to-use appliance, buy a device that comes with it preinstalled, or find a service provider to host it for you.

The server is written in PHP and JavaScript under the AGPL-3.0 license. Nextcloud GmbH also offers an Enterprise edition aimed at public sector, education and company users. It suits households, schools and organizations that want to replace commercial cloud storage and office suites with something they run themselves.

Mail-in-a-Box helps individuals take back control of their email by providing a one-click, easy-to-deploy mail server in a box. It turns a fresh Ubuntu 22.04 LTS 64-bit machine into a working mail server by installing and configuring the required components. There are no user-configurable setup options, so it is designed to just work.

The installed components include Postfix for SMTP, Dovecot for IMAP, Nextcloud for CardDAV and CalDAV, z-push for Exchange ActiveSync, and Roundcube webmail. It adds spam filtering with SpamAssassin and greylisting with Postgrey, DNS with SPF, DKIM, DMARC, DNSSEC, DANE TLSA, MTA-STS and SSHFP records set automatically, and TLS certificates from Let's Encrypt. Backups use duplicity, with ufw, fail2ban and munin for protection and monitoring.

Project goals include making a good mail server easy to deploy, promoting decentralization and privacy, and keeping configuration automated, auditable and idempotent. It deliberately does not aim to be customizable by power users. Mail-in-a-Box is written in Python, released into the public domain under CC0-1.0, and has a Code of Conduct for contributors.

Stalwart is an open-source mail and collaboration server written in Rust and designed to be secure, fast, robust and scalable. It supports JMAP, IMAP4, POP3, SMTP, CalDAV, CardDAV and WebDAV, so a single server can handle email, calendars, contacts and file storage.

On the email side it offers JMAP for Mail and Sieve, IMAP4rev2 and IMAP4rev1 with ManageSieve, and POP3. The SMTP server includes DMARC, DKIM, SPF and ARC for message authentication, transport security through DANE, MTA-STS and TLS reporting, automated DKIM key rotation, throttling and filtering rules, sieve scripting and milter integration, and distributed virtual queues.

The collaboration features cover CalDAV and JMAP for Calendars, CardDAV and JMAP for Contacts, and WebDAV and JMAP for File Storage, with fine-grained sharing through WebDAV ACL and JMAP Sharing. A built-in spam and phishing filter includes a rule set and LLM-driven message analysis. It is self-hosted software that administrators run on their own servers.

mailcow: dockerized is an open-source mail server package that runs as a set of Docker containers managed with Docker Compose. It bundles the pieces needed to run your own email, so administrators do not have to assemble and configure each component separately.

The stack is built around established open-source software: Postfix for SMTP, Dovecot for IMAP, Rspamd for spam filtering, ClamAV for antivirus scanning, SOGo for groupware and webmail, and ACME support for certificates. A web administration interface sits on top. Topics in the repository also mention the Olefy component for document scanning.

mailcow is released under the GNU General Public License v3 and installed on your own server following the official documentation. It is managed and maintained by The Infrastructure Company GmbH, and the project offers support contracts through Servercow as well as a one-time support payment option. The community gathers on Telegram, Mastodon and GitHub Sponsors.

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++.

Modoboa is an open-source email server that comes with a modern web interface for administration. Its pitch is that running your own mail server should not require deep technical knowledge: the project says setup takes under ten minutes. It positions itself against paid mailboxes from internet providers, free webmail services that monetize your data, and doing everything by hand.

Under the hood it brings together established open-source components, including Postfix, Dovecot and Rspamd, behind a single interface. The resulting server offers the usual hosting features: webmail, calendars, address books, filtering rules to organize messages, an auto-responder, and unlimited domains, mailboxes and aliases. An administration panel covers managing all of these.

Modoboa is written in Python with Django and a Vue front end, and it is released under the ISC license. You host it yourself, which suits small businesses, associations and individuals who want control over their email and privacy. The website also lists a Modoboa Pro offering and a sponsoring page for supporting development.

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.

SOGo is an open-source groupware suite that combines calendaring, address book management and a full webmail client, along with resource sharing and permission handling. It is described as fast and scalable, and it is written mainly in Objective-C with an AngularJS Material web interface. It is licensed under GPL-2.0 and developed by Alinto.

Because SOGo relies on documented standards such as IMAP, CalDAV and CardDAV, it provides native connectivity without plugins to many clients, including Microsoft Outlook, Apple iCal, the iPhone, Mozilla Lightning and many mobile devices. A Thunderbird connector extension for Thunderbird 78 and later is available in a separate repository.

Building SOGo requires the source of both SOGo and SOPE, the underlying application server framework, and a FAQ covers compilation. A dev container is available for development. The project welcomes documentation work, feature requests, mailing list participation, patches and translations, and the README lists official translations in many languages with their maintainers.