Nextcloud
A self-hosted, open-source platform for file sharing, collaboration, and productivity tools like calendars, contacts, and more. Fully GDPR compliant and EU-based.
Nextcloud is an open-source alternative to:

Nextcloud is a self-hosted productivity platform that provides a safe home for all your data. It offers secure file sharing, collaboration tools, and a suite of integrated applications like calendars, contacts, mail, and more.
Key Features
- Secure File Storage & Sharing: End-to-end encrypted file storage with granular access controls and file versioning.
- Collaboration Suite: Built-in tools for document editing, calendars, contacts, mail, and video conferencing.
- App Ecosystem: Extensible with over 200+ community and official apps for enhanced functionality.
- Self-Hosted & Private: Full control over your data with no third-party access or tracking.
- GDPR Compliant: Designed with privacy in mind, meeting strict EU data protection regulations.
- Cross-Platform Support: Available on desktop, mobile, and web with seamless synchronization.
- Open Source: Transparent codebase with active community and enterprise support options.
- Enterprise Features: Advanced security, scalability, and compliance tools for business use.
Tech / Self-Hosting
Nextcloud is built with PHP and uses a relational database (MySQL, PostgreSQL, MariaDB) for storage. It supports Docker, Snap packages, and traditional server installations. The platform is highly scalable and can be deployed on-premises or in cloud environments. Comprehensive documentation and community support are available for self-hosting setups.