SilentSuite
Open-source, zero-knowledge sync for calendars, contacts, and tasks. It keeps plaintext off the server and keys on trusted devices.
Synchronise calendars, contacts, and tasks with end-to-end encryption while keeping your personal data unreadable to the server. This privacy-first sync platform helps individuals, families, professionals, and organisations securely manage schedules, address books, and reminders across multiple devices without exposing sensitive information to a hosted service.
Private Calendar, Contact, and Task Sync With End-to-End Encryption
Instead of storing readable calendar events, contacts, and tasks on a cloud server, this platform encrypts your data on trusted devices before it is synchronised. The server stores only encrypted ciphertext, allowing secure syncing without access to event titles, contact details, task descriptions, or other personal information.
Whether you choose the hosted service or deploy your own server, your data remains encrypted throughout the synchronisation process.
Key Features
End-to-End Encrypted Synchronisation
Keep your personal information private across every device.
Securely synchronise:
- Calendars
- Contacts
- Tasks
- Reminders
- Personal information
using end-to-end encryption.
Device-Side Encryption
Encrypt records before they leave your device.
The platform ensures:
- Plaintext stays on trusted devices
- Servers receive encrypted data only
- Sensitive information remains protected
- Client-side encryption
- Privacy-first synchronisation
throughout the sync process.
Open Source Platform
Use transparent, auditable software.
The project includes open-source:
- Server
- Web application
- Sync bridge
- Self-hosting components
- Client tools
released under the AGPL-3.0-only licence.
Self-Hosting Support
Run your own encrypted sync server if preferred.
Deploy on your own infrastructure while maintaining:
- Full data ownership
- Server control
- Independent hosting
- Privacy
- Flexible deployment
for complete control over your environment.
Standard Calendar & Contact Compatibility
Continue using the applications you already know.
Compatible with:
- CalDAV
- CardDAV
- Calendar clients
- Contact managers
- Task applications
through bridge support.
Wide Client Support
Access encrypted data across popular platforms.
Supported clients include:
- Web app
- Android
- Apple Calendar
- Thunderbird
- Outlook
- GNOME Evolution
- KDE Kontact
- Tasks.org
- Other CalDAV/CardDAV-compatible applications
for flexible multi-device use.
Secure Cryptographic Design
Protect data using modern encryption technologies.
The platform uses:
- Etebase protocol
- XChaCha20-Poly1305 encryption
- Argon2id key derivation
- Device-held encryption keys
- Zero-knowledge synchronisation
to keep data unreadable to the server.
Export & Backup Options
Retain ownership of your information.
Export your data using:
- ICS calendar files
- VCF contact files
- ZIP backups
- Standard formats
- Portable archives
for migration or backup purposes.
Hosted & Self-Hosted Flexibility
Choose the deployment model that best fits your needs.
Options include:
- Hosted cloud service
- Self-hosted server
- Unlimited devices
- Free trial
- Migration between deployments
without vendor lock-in.
Privacy-First Architecture
Keep sensitive information under your control.
The platform is designed so that:
- Servers cannot read calendar events
- Contact information remains encrypted
- Task content stays private
- Encryption keys remain on trusted devices
- Synchronisation never exposes plaintext
during storage or transit.
Built for Private Personal Information Management
The platform combines encrypted calendar synchronisation, secure contact management, private task syncing, self-hosting, open-source software, cross-platform compatibility, and standard export formats into one privacy-focused personal information management solution.
Key benefits include:
- Encrypted calendar sync
- Secure contact synchronisation
- Private task management
- End-to-end encrypted CalDAV
- Open-source sync platform
Built For
- Privacy-Conscious Individuals
- Professionals
- Families
- Open Source Enthusiasts
- Self-Hosting Users
- Organisations
Common Use Cases
- Synchronising calendars securely
- Managing encrypted address books
- Syncing personal task lists
- Running a self-hosted calendar server
- Sharing calendars privately
- Backing up contacts and events using open formats
Why It Matters
Calendars, contacts, and task lists often contain some of the most sensitive personal information people store online. Traditional cloud services typically have access to this data in readable form. This platform takes a different approach by encrypting every record on trusted devices before synchronisation begins, ensuring the server stores only encrypted ciphertext. With open-source components, self-hosting support, compatibility with standard CalDAV and CardDAV clients, portable exports, and modern cryptography using the Etebase protocol, XChaCha20-Poly1305, and Argon2id, users can synchronise personal information while maintaining control over both their data and infrastructure.
Synchronise Calendars, Contacts, and Tasks Without Giving Up Privacy
Encrypt calendar events, contacts, and tasks before they leave your device, synchronise securely across web, Android, Apple Calendar, Thunderbird, Outlook, and other CalDAV/CardDAV clients, export data in standard formats, choose between hosted or self-hosted deployments, and keep your personal information private with end-to-end encryption and open-source software.
