SigNoteSigNote
Documentation

About SigNote āœ¦

SigNote is an end-to-end encrypted notes app with three security tiers. Anything you mark as sensitive is encrypted in your browser before it leaves your device, so the server stores ciphertext it has no way to read.

The core idea is simple: the app should not be able to read what you did not choose to show it. You pick the security level for each note, and the keys stay with you ā€” there is no password to reset, because there is nothing on the server that could undo the encryption.

Three tiers of privacy šŸ”

Not every note needs to be a secret. SigNote lets you choose the right privacy level for each piece of information:

TierNameEncryptionBest for
1NotesNoneEveryday notes, to-dos, ideas
2SecretsAES-GCM, shared session keyPasswords, private info you access often
3SealsAES-GCM, unique per-note keyYour most sensitive data

All tiers support file attachments ā€” images render inline, other files appear as download cards. For Secrets and Seals, files are encrypted client-side before upload, just like note bodies. ā†’ File uploads

All encryption and decryption happens in your browser. The server only ever stores ciphertext ā€” it never sees your plaintext note bodies or any key material capable of decrypting them.

How identity works šŸŖŖ

There is no password anywhere in SigNote. Pick whichever way of proving who you are suits you:

  • Passkey ā€” Use your fingerprint, face, screen lock, or security key. The private key stays with your device.
  • Email code ā€” Enter your address, get a six-digit code, and you're in. Signing up and signing in are the same step.
  • Google ā€” One click, if you already have a Google account.
  • Sign-In with Ethereum (SIWE) ā€” Sign a message with your wallet. No email address is involved, so an account created this way is anonymous.
  • Passkeys ā€” Coming soon.

You can link several methods to the same account, so how you signed up doesn't lock you in.

Whichever you choose, it only governs access to your account. The passphrase that unlocks Secrets and Seals is a separate thing, and no sign-in method can substitute for it.

ā†’ Learn more in Sign in

How encryption works šŸ”‘

For Secrets and Seals, encryption is unlocked with a passphrase you choose during setup. The passphrase is never stored ā€” instead, SigNote derives a Master Encryption Key (MEK) by combining a passphrase-derived share with a server-side share. Neither side alone can reconstruct the key.

ā†’ Deep dive in Encryption

Open source

SigNote is open source and available on GitHub. It doubles as a reference project for client-side encryption, note security tiers, and passwordless authentication in a modern Next.js app.

šŸ‘‰ github.com/irondsd/signote

Issues, ideas, and contributions are very welcome.

Another project

Iā€™m also building Factura.uno ā€” a way to turn household utility bills into a clear record of what a property costs. Upload PDF bills to extract amounts, consumption, billing periods, and providers, then follow spending trends and projected expenses over time.

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