Notesnook

Notesnook is a secure, encrypted note-taking app built around one principle: your notes are yours alone. Every note is encrypted on your device before it syncs anywhere. The company can't read your data. Neither can anyone else.

It's a direct alternative to Evernote, OneNote, and similar apps that store your notes in plaintext on their servers. Notesnook takes a different approach with XChaCha20 encryption and Argon2 key derivation, and you can verify it yourself using their open source tool, Vericrypt, which works entirely offline against real account data.

The full client and sync server are open source. You can self-host the sync server if you want complete independence from their infrastructure.

Key features:

• End-to-end encryption on every note, notebook, and attachment, at rest and in transit
• Cross-device sync across mobile, desktop, and browser, all encrypted
• Notes vault for password-protecting your most sensitive notes with an additional layer of encryption
• App lock that automatically locks your database when you step away
• Rich editor with tables, task lists, math formulas, code blocks, image embeds, outlines, and Markdown