Zero-Knowledge Encryption: Your Business Is None of Ours
Your task list is one of the most intimate digital artifacts you own. It knows what you're working on, what you're avoiding, what keeps you up at night, and what you're planning next. So why do most task apps store all of that in plaintext on their servers?
Your Tasks Say More Than You Think
Consider what a typical week in a task manager reveals:
- Health: "Book dermatologist appointment," "Refill prescription," "Therapy at 3pm"
- Finances: "Pay credit card," "Review loan application," "Tax documents to accountant"
- Career: "Update resume," "Prepare for interview at [Company]," "Research salary negotiation"
- Relationships: "Anniversary dinner reservation," "Call divorce lawyer," "Couples counseling Thursday"
This isn't hypothetical. This is what real task lists contain. And at most productivity apps, this data sits in plaintext on servers that employees can access, governments can subpoena, and attackers can breach.
In January 2024, a threat actor scraped 15 million Trello user records through a publicly exposed API and listed them for sale on a dark web forum. The data included emails, usernames, and full names. Trello's response? They restricted the API to require authentication — a fix that should have been the default from day one.
What Zero-Knowledge Actually Means
"Encryption" is a word that gets thrown around loosely. Most apps offer encryption in some form. The question is: who holds the keys?
| Encryption Type | Who Has the Keys | What a Breach Exposes |
|---|---|---|
| In transit (TLS) | Server decrypts on arrival | Everything, once on the server |
| At rest (AES-256) | Provider holds the keys | Everything, if keys are compromised |
| Zero-knowledge | Only you hold the keys | Nothing readable, even with full server access |
With zero-knowledge encryption, your data is encrypted on your device before it leaves. The server stores ciphertext it cannot decrypt. We don't hold the keys. Neither can our engineers, our database administrators, or anyone who might gain unauthorized access to our infrastructure.
Clairvoyant uses zero-knowledge encryption by default — the same model used by Signal for messages and Proton for email. The server stores ciphertext it cannot decrypt. No major task management app does this.
If you want AI features without running models on your own hardware, you can opt in to Server-Assisted AI, where our server temporarily decrypts your tasks in memory to run AI features, then immediately discards the plaintext. Your data is never stored unencrypted, never sent to any third-party AI provider. But this is your choice — it's never enabled without your explicit consent. Learn how Server-Assisted AI works →
The Competitive Landscape Is Bleak
We looked at every major productivity tool on the market:
| App | End-to-End Encrypted | Encryption Model |
|---|---|---|
| Todoist | No | Provider-held keys |
| Notion | No | AES-256 at rest, provider-held keys |
| Asana | No | AES-256 at rest, SOC 2 compliant |
| Trello | No | Standard TLS + at rest |
| TickTick | No | Standard encryption |
| Google Tasks | No | Google infrastructure encryption |
| Monday.com | No | SSO + audit logs, no E2EE |
| Clairvoyant | Yes | Zero-knowledge by default, user-held keys |
These apps ask you to trust them with your data. They promise responsible handling through privacy policies and compliance certifications. But trust-based models have a fundamental flaw: they create a single point of failure. When the provider's key management is compromised, every user's data is exposed at once.
How Clairvoyant's Encryption Works
Clairvoyant is a local-first application. Your data lives on your device first, and syncs to the cloud as an encrypted backup. This architecture makes zero-knowledge encryption practical without sacrificing features.
- Key derivation: When you create your account, your password generates a unique encryption key using PBKDF2 with 100,000 iterations
- Client-side encryption: Task content (titles, descriptions, notes) is encrypted with AES-256-GCM before leaving your device
- Encrypted sync: Our server receives and stores only ciphertext
- Local decryption: When you sign in on another device, your password derives the same key and data decrypts locally
Search, filtering, and sorting all run against your local data. By default, the server is purely a sync and backup target — it cannot read any of it. If you opt in to Server-Assisted AI, our server can temporarily process your data in memory for AI features, but it's never stored in plaintext and never sent to third-party AI providers.
The Trade-Off We Think Is Worth It
Zero-knowledge encryption means we can't reset your password. If we could, that would mean we have access to your encryption keys, which would defeat the entire purpose.
Instead, you receive a 24-word recovery key during account creation. This is the only fallback if you forget your password. It's the same model Proton uses, and for the same reason: genuine privacy requires that the user, not the provider, controls access.
We know this adds friction. We think the alternative — a company having plaintext access to your most personal data — is worse.
Why This Matters Now
The average cost of a data breach reached $4.44 million in 2025. Breach detection takes an average of 194 days. In 2024 alone, 1.3 billion breach notification letters were sent — more than triple the previous year. Privacy regulations now cover 75% of the global population.
The productivity tool market has largely ignored these realities, relying on compliance certifications and trust-based models while storing user data in formats they can read. That model worked when the stakes were lower. With task managers increasingly containing health information, financial details, career plans, and personal relationships, the stakes are no longer low.
Your tasks are your business. Zero-knowledge encryption is the default — a mathematical guarantee that we can't read your data. If you choose to opt in to Server-Assisted AI, your data is processed in memory and immediately discarded — never stored in plaintext, never sent to a third-party AI provider. Either way, you're in control.