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Best Free & Open Source Alternatives to Google Calendar

Compare 3 open-source Google Calendar alternatives including Nextcloud , ownCloud and Mitra

If you're looking for the best open-source alternative to Google Calendar, Nextcloud is a strong place to start. If it doesn't quite fit your needs, there are plenty of other great options worth exploring, including ownCloud and Mitra. We've ranked the top alternatives to help you compare your options and find the right fit.

#1Nextcloud

Nextcloud

The most popular self-hosted cloud platform for file storage, collaboration, and communication.

Nextcloud is the world's most popular open-source, self-hosted cloud platform. It started as a file sync and share solution (like Dropbox or Google Drive) and has evolved into a comprehensive productivity suite with files, calendar, contacts, email, talk (video/chat), and hundreds of apps available through the Nextcloud App Store.

Nextcloud Files provides desktop sync clients for Windows, macOS, and Linux, as well as mobile apps for iOS and Android. Files can be shared with granular permissions, encrypted, and version-controlled. The platform integrates with ONLYOFFICE and Collabora Online for in-browser document editing, effectively replicating the full Google Workspace experience on your own infrastructure.

With over 34,000 GitHub stars and licensed under AGPL-3.0, Nextcloud is the gold standard for self-hosted cloud storage. It is deployable on any Linux server, available as a one-click install via Docker, and maintained by Nextcloud GmbH with an active enterprise support offering. For organizations wanting to replace Google Drive and the broader Google Workspace, Nextcloud is the most complete solution.

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#2ownCloud

ownCloud

ownCloud is the pioneering open-source file sync and sharing platform. Self-host your cloud for files, calendars, contacts, and collaboration — your data.

ownCloud is the original open-source file sync and sharing platform that pioneered the concept of self-hosted cloud storage and directly inspired the creation of Nextcloud. It provides a complete solution for storing, syncing, and sharing files across devices with a user experience similar to Google Drive, but on infrastructure you control.

ownCloud offers desktop sync clients for all major operating systems and mobile apps for iOS and Android. Files can be shared with internal and external users with fine-grained permissions. Enterprise features include SSO integration, antivirus scanning, encryption at rest, and audit logging. The ownCloud Infinite Scale (oCIS) project is a modern, cloud-native rewrite of the platform built for scalability.

With over 8,700 GitHub stars and licensed under AGPL-3.0, ownCloud is widely deployed across enterprises and public sector organizations. It is a battle-tested, enterprise-grade alternative to Google Drive for organizations that require compliance, data sovereignty, and professional support.

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#3Mitra

Mitra

A self-hosted calendar and task planner in one, with two-way CalDAV, Google Calendar, and Apple Calendar sync.

Mitra is a self-hosted web calendar that puts your events and your tasks on the same timeline, so you can see when you actually have room to get things done. It runs as a single Docker container on your own server with no telemetry and a database you own, and it is free under AGPL-3.0.

In week, month, year, timeline, and table views you can drag to create, move, and resize events and tasks alike. Tasks without a date wait in a Planning tab with a due date and an estimate until you drag them into your week, and the app supports availability, subtasks, dependencies, push-notification reminders, and guest lists with replies. A command palette makes it fully keyboard-driven.

Mitra keeps its own calendars or syncs two ways with CalDAV, Google Calendar, Apple Calendar, Notion, and Tempo; published feeds come in as read-only subscriptions. That makes it easy to run alongside the tools you already use instead of replacing them all at once.

Unlike Google Calendar, your schedule is not attached to an ad-supported Google account, and unlike Todoist or Fantastical, there is no pro subscription gating features like reminders or scheduling views. Mitra is early and moving fast — expect rough edges and breaking changes before the 1.0 release — but it already ships a demo instance if you want to try it before hosting.

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Frequently Asked Questions

Are there any open source alternatives to Google Calendar?

Yes, there are 3 open source alternatives to Google Calendar. Popular options include Nextcloud, ownCloud, Mitra. These alternatives are free to use and many offer self-hosting options.

What is the best free alternative to Google Calendar?

The best free alternative to Google Calendar depends on your specific needs. Nextcloud is a popular choice with self-hosting capabilities. All alternatives listed here are open source and free to use.

Can I self-host an alternative to Google Calendar?

Yes, 3 of the alternatives listed here can be self-hosted, giving you complete control over your data and privacy.

Why should I switch from Google Calendar to an open source alternative?

Open source alternatives to Google Calendar offer several advantages: no vendor lock-in, complete data ownership, no subscription fees, the ability to self-host for privacy and security, and active community support. You can also customize the software to fit your specific needs.

Google Calendar

Google Calendar

Google Calendar is Google free time-management and scheduling service, part of the Google Workspace suite. It lets users create and share events, set reminders, and sync across devices through their Google account.

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Notion

Notion

Notion is an all-in-one AI-powered workspace that combines notes, tasks, wikis, databases, and project management tools into a unified platform. It enables teams and individuals to centralize information, automate repetitive workflows, and collaborate seamlessly—from simple docs to advanced knowledge bases and live project tracking.

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Discord

Discord

Discord is a free communication platform that lets people connect through text, voice, and video across customizable communities called “servers.” Originally popular among gamers, it has expanded into a hub for all kinds of groups—ranging from study clubs and fandoms to professional teams—thanks to features like topic-based channels, screen sharing, live streaming, and integrations with other apps. Its mix of casual chat and organized spaces makes it a versatile tool for both socializing and collaboration.

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1Password

1Password

1Password is a commercial password manager developed by AgileBits. It stores login credentials, credit card details, software licenses, secure notes, and other sensitive information in encrypted vaults protected by a master password and a Secret Key. The service is available on macOS, Windows, Linux, iOS, Android, and as browser extensions, with data syncing across devices through 1Password's cloud. Features include a built-in password generator, secure sharing of vaults between users, and Watchtower, which flags weak, reused, or compromised passwords. 1Password offers plans for individuals, families, and businesses, with shared vaults, role-based access controls, and admin tools for team management. It uses a zero-knowledge architecture with end-to-end AES-256 encryption, meaning data is encrypted on the user's device and 1Password cannot access the contents of stored vaults. Pricing follows a subscription model with monthly or annual billing; no free tier is available, though a trial period is offered.

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Google Analytics

Google Analytics

Google Analytics is a web analytics service by Google that tracks and reports website traffic. It helps businesses and individuals understand user behavior, measure performance, and optimize content by providing insights into visitor demographics, sources, and engagement patterns.

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Goodreads

Goodreads

Goodreads is Amazon's social cataloging platform for books, allowing users to track books they have read, are reading, or want to read. It offers reviews, recommendations, reading challenges, and community features for book enthusiasts.

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Jira

Jira

Jira is a proprietary project management and issue tracking tool by Atlassian, widely used for agile software development, sprint planning, and bug tracking.

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ChatGPT

ChatGPT

OpenAI's flagship conversational AI assistant, with chat, image generation, code execution, and plugins for general-purpose tasks.

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Claude Code

Claude Code

Anthropic's official CLI for running Claude in your terminal — agentic coding with file edits, bash, and tool use driven by the Claude API.

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Google Authenticator

Google Authenticator

Google Authenticator is a free mobile app developed by Google that provides two-factor authentication (2FA) to enhance account security. It generates time-based, one-time passcodes (TOTP) or counter-based codes (HOTP) that users enter along with their password when signing into supported services. By scanning a QR code or entering a setup key, users can link the app to their accounts, ensuring that even if a password is stolen, unauthorized access is far less likely without the corresponding code from the app. It works offline, making it both secure and convenient for protecting online accounts.

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TV Time

TV Time

TV Time is a mobile app for tracking TV shows and movies you watch. It lets you log episodes, discover new content, read reviews, and connect with other fans. Owned by Whip Media, it is one of the most popular media tracking apps with millions of users worldwide.

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Adobe Photoshop

Adobe Photoshop

Adobe Photoshop is the industry-standard image editing and graphic design software used by photographers, designers, and digital artists for photo manipulation, compositing, and digital painting. Part of the Adobe Creative Cloud suite.

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Adobe Premiere Pro

Adobe Premiere Pro

A professional video editing application by Adobe, widely used for film, TV, and web video production.

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