Your Private Space for Notes, Thoughts & Secrets
The premier Android diary engineered with client-side zero-knowledge encryption. Your words are encrypted on your device with AES-256 before ever syncing to the cloud. What you write stays yours alone—forever.
See Zero-Knowledge Encryption in Action
Type anything below. Watch your browser's native Web Crypto API execute the exact same AES-256-GCM algorithm our Android app uses. Notice how only encrypted ciphertext leaves your device.
Client-Side Encryption Pipeline
Argon2id Key Wrapping • 12-byte IV Nonce • 128-bit Authentication Tag
Everything You Need for a Peaceful Mind
Combining the privacy of an offline bank vault with the elegance of modern Android Material 3 design and effortless cloud sync.
True Zero-Knowledge AES-256-GCM
Your notes are encrypted directly on your phone using a 256-bit Master Key generated by your device. The server only ever stores unintelligible ciphertext. Even if our servers were seized or breached, your personal entries remain mathematically impossible to read.
Biometrics & Vault PIN
Unlock with a fingerprint touch, facial recognition, or a custom 6-digit PIN. Lock the whole app or individual sensitive notes.
Categories & Moods
Organize your journaling effortlessly across dedicated life spaces with customizable badges and mood indicators.
In-Note Checklists
Blend daily stream-of-consciousness journaling with actionable habits, morning routines, and to-do checkmarks.
Instant Google Drive & Cloud Backup
Switching devices or upgrading phones? Keep your memories completely safe. Secret Diary offers automated encrypted snapshots and native Google Drive sync. Even in the cloud, everything remains strictly encrypted with your personal keys.
Explore the App Interface
Click through the tabs below to preview how Secret Diary feels in your hands.
Interactive Daily Notes & Rich Checklists
Capture thoughts instantly with color-coded categories, mood badges, customizable icons, and interactive to-do checkboxes right inside each diary entry.
- ✔ Fast offline-first local SQLite cache with immediate responsiveness
- ✔ Argon2id password-derived wrapping key ensures zero plaintext exposure
- ✔ Daily reminder notifications to build a fulfilling journaling habit
Invest in Your Peace of Mind
Enjoy full offline zero-knowledge journaling for free, or unlock unlimited cloud backups and multi-device capabilities with Premium.
Standard (Free)
The essential private diary for everyday thoughts.
- Full Client-Side AES-256 Encryption
- Biometric & PIN Vault Lock
- Checklists, Tags & Mood Categories
- Calendar Dot Matrix View
- 100% Ad-Free Private Experience
Premium Vault
Unlimited encrypted cloud sync, auto-backups, and priority support.
- Everything in Standard, plus:
- Automatic Instant Cloud Backups
- Seamless Google Drive Integration
- Unlimited Rich Media Attachments
- VIP Priority Support from Developers
Loved by People Who Value Privacy
Here is what people write about their experience using Secret Diary every day.
"Finding a diary app that genuinely doesn't sell your data or read your entries is almost impossible today. Secret Diary's zero-knowledge cryptography gives me total peace of mind."
"The biometric unlock is instantaneous, and the Material 3 UI with the custom purple theme is gorgeous. The in-note checklists transformed how I plan my days."
"I bought the yearly premium plan immediately. Automatic Google Drive backup with AES encryption means I'll never lose my personal reflections even if I lose my phone."
Frequently Asked Questions
Everything you need to know about our encryption, key escrow, and data safety.