Why I Started SilentSuite, an Encrypted Alternative to Google Calendar

Open your calendar right now and look at the last month. Doctor appointments. Job interviews. Therapy sessions. Date nights. Meetings with your lawyer. Every recurring commitment. Every cancelled plan. Your calendar doesn't just track your schedule. It tells the complete story of your life. That is the data SilentSuite was built to protect.

Now look at your contacts. Your family. Your therapist. Your ex. Your doctor. The relationships between them. Phone numbers, birthdays, home addresses. It's a map of every person who matters to you.

This data is deeply personal. And for most people, every bit of it sits on servers owned by Google, Apple, or Microsoft. Fully readable, fully analysable, and fully available to anyone with the right court order, the right exploit, or the right employee badge.

Why isn't your calendar end-to-end encrypted already?

We have encrypted messaging now. Signal proved you could have a great user experience and end-to-end encryption. WhatsApp adopted the same protocol for billions. Proton built encrypted email. Bitwarden and 1Password encrypt your passwords.

But calendars? Contacts? Tasks? The data that structures your entire life is still sitting unencrypted on someone else's server.

Google Calendar uses TLS in transit and encrypts data “at rest”, which means Google holds the keys. They can read every event. Their systems process your calendar to show you smart suggestions, travel times, and reminders. That processing requires access to unencrypted data. Apple is better: iCloud offers Advanced Data Protection for some categories. But calendar and contacts are explicitly excluded from E2E encryption even with ADP enabled. I walk through Google, Apple, Microsoft, Proton, Tuta, Nextcloud, and SilentSuite one by one in who can read your calendar.

This isn't a theoretical risk. Any provider that can read your events can also disclose them: to an attacker who reaches the database, to an employee with the right access, or to a government that serves a lawful request. And nobody needs a breach to learn something. Even without event contents, patterns in who you meet and when reveal relationships and routines.

Why did I start SilentSuite?

SilentSuite exists because I believe your schedule and relationships deserve the same level of protection as your messages. The technology for this has existed for years. The Etebase protocol, created by the EteSync project, solved the hard cryptographic problems: zero-knowledge sync, end-to-end encrypted collections, conflict resolution, and offline-first architecture.

Then EteSync stopped. The protocol stayed sound, and one corner kept moving: the Android app still ships occasional releases, and hosted signup is still open. But the project is now mostly abandoned. The server repository has not been committed to since July 2024, the JavaScript client not since early 2023, and the iOS app has been dormant since 2022. The maintainer said in a status update published 2023-12-20 that “I have much less time than before so the development of the apps has slowed down,” and the GitHub organisation shows how far that went. The pace no longer matched what people were depending on.

So I decided to pick it up. Take the proven Etebase protocol and build a modern, maintained product around it. Not a weekend project or a hobby. A real service, with a real business model, that people can actually depend on. SilentSuite is still my solo project, with contributors helping improve it along the way. If you are coming from EteSync specifically, the EteSync alternative guide covers what carries over and how to move your data.

What is SilentSuite?

SilentSuite is encrypted sync for the rest of your digital life:

• Calendar: your events, encrypted before they leave your device
• Contacts: your relationships, visible only to you
• Tasks: your to-dos, your plans, nobody else's business

Here's what I care about:

1. Encryption is not a feature. It's the architecture.

Every piece of data is encrypted on your device before it ever touches the SilentSuite server. SilentSuite doesn't offer a toggle to “enable encryption” because there's nothing to toggle. The server only ever sees ciphertext. I couldn't read your data even if I wanted to, or if I were compelled to. For the precise version of that claim, see What SilentSuite actually encrypts and SilentSuite's threat model, which covers the cases encryption does not cover.

2. Open source by default

SilentSuite's apps and server are open source. You can read the code, audit the encryption, and verify SilentSuite's claims. Privacy promises without transparency are just marketing. I back that claim with code.

3. No lock-in, ever

Your data is yours. Export it anytime. Self-host the server if you want. SilentSuite uses the standard Etebase protocol, not a proprietary format designed to keep you trapped. The way to keep customers is to build a great product, not to make leaving impossible.

4. Your Data, Your Control

With end-to-end encryption and zero-knowledge architecture, your data is protected regardless of where the server is located. SilentSuite complies with GDPR and privacy best practices, and because the server is open source, you can self-host for complete data sovereignty. Neither I nor any third party can access your unencrypted data.

5. Sustainable business, not a hobby project

Too many privacy tools are side projects that disappear when the maintainer gets busy. SilentSuite has a real business model: a paid hosted service, priced fairly, that funds continued development. I charge enough to sustain the project, and I don't supplement revenue by monetising your data. I can't. It's encrypted.

Who is SilentSuite for?

SilentSuite is for people who care about privacy but don't want to run their own server. The “privacy middle class”: people who use Signal, who chose Proton Mail, who switched to Bitwarden, but who still sync their calendar through Google because there wasn't a good alternative.

You shouldn't need a homelab and a computer science degree to keep your calendar private. It should be as easy as signing up and installing an app.

What happens next?

SilentSuite is available now as a public beta. The Etebase server is deployed, end-to-end encrypted sync works between devices, and the web and Android clients are in users' hands. Early-adopter hosted plans start at €3/mo billed annually, and the AGPL-3.0 server can be self-hosted instead.

The SilentSuite roadmap, roughly:

1. Now: Public beta with the server live, web and Android apps available, and the core protocol verified
2. Soon: A wider set of tested desktop client paths through the local CalDAV bridge (how the bridge works)
3. On the roadmap, coming soon: native iOS app and family plans
4. Future: B2B offering for organisations that need compliant, encrypted PIM

I'm building this in public. I'll share progress, decisions, and the occasional hard lesson on this blog.

FAQ

What is SilentSuite?
SilentSuite is an open-source, end-to-end encrypted alternative to Google Calendar, Contacts, and Tasks. It is built on the Etebase protocol, encrypts your data on your device before it is uploaded, and is available now as a public beta.

Why is Google Calendar not end-to-end encrypted?
Because its features need to read your events. Smart suggestions, travel-time estimates, and event detection from Gmail all require server-side access to plaintext, so Google holds the keys and encrypts only in transit and at rest.

Is SilentSuite open source?
Yes. The server and the desktop bridge are AGPL-3.0 and the Android app is GPL-3.0, so the encryption can be inspected rather than taken on trust.

How much does SilentSuite cost?
Hosted plans start at “From €3/mo” on the Early Adopter annual plan during public beta. Self-hosting the AGPL-3.0 server is free; you pay only for the infrastructure you run.

Does SilentSuite work on iOS?
Not today. Android, the web app, and supported desktop clients through the local CalDAV bridge work now. iOS is on the roadmap, coming soon, and is not currently supported.

If this sounds like something you've been waiting for, get started today. No spam. No data harvesting.

Your calendar is your life. It should be yours alone.