Secure Notes

How do I keep encrypted notes that never leave my browser?

Create a vault protected by a master passphrase. Your notes are encrypted with real AES-256-GCM — the key is stretched from your passphrase with PBKDF2-HMAC-SHA-256 over a random salt via the Web Crypto API — and only the resulting ciphertext is saved to this browser’s IndexedDB. Unlock to read and search them in memory, and lock to wipe the plaintext. Nothing is ever uploaded, synced or sent to a server; if you forget the passphrase the notes cannot be recovered.

One master passphrase unlocks a vault of notes; create, edit, delete and search
AES-256-GCM with a PBKDF2-HMAC-SHA-256 key (210,000 iterations, random salt + IV)
Only the ciphertext is stored (IndexedDB) — never plaintext
Export / import the still-encrypted vault to back it up or move it; change the passphrase to re-encrypt
Optional idle auto-lock; forgetting the passphrase means the notes are unrecoverable

What is

Encrypted notes vault

An encrypted notes vault is a private notepad whose contents are protected by a passphrase using authenticated encryption. In this tool the entire set of notes is serialised and encrypted as a single AES-256-GCM (RFC 5116) blob, with the encryption key derived from the passphrase by PBKDF2-HMAC-SHA-256 (RFC 8018) over a random salt using the browser’s Web Crypto API. Only that ciphertext is persisted, in the browser’s IndexedDB — the plaintext exists only in memory while the vault is unlocked, and there is no key escrow, so a lost passphrase means lost notes.

Security & Privacy

Related terms

AES-256-GCMPBKDF2HMAC-SHA-256authenticated encryptionkey derivationsaltIV / nonceWeb Crypto APIIndexedDBzero-knowledgepassphrasethreat model

Frequently Asked Questions

This tool is 100% client-side. Your notes are serialised and encrypted with AES-256-GCM using a PBKDF2-HMAC-SHA-256 key derived from your passphrase, all via the Web Crypto API, and only the resulting ciphertext blob is written to this browser’s IndexedDB. Nothing is uploaded, there is no account, no cloud sync and no analytics, and locking the vault wipes the decrypted notes and passphrase from memory. Because the data lives only in this browser, it is also not backed up for you — export the encrypted vault yourself if you want a copy.

No. Notes are encrypted in your browser and only the ciphertext is saved to this device’s IndexedDB. There is no server, upload, sync or telemetry.

The passphrase is never stored anywhere — it is only used, in memory, to derive the decryption key. That means nobody, including this tool, can recover your notes if you forget it: a correct passphrase is the only way to pass AES-GCM’s authentication and decrypt the vault. Choose something you can remember but that is hard to guess, use the built-in strength meter or random generator, and write it down somewhere safe. Keep an exported backup of the encrypted vault too, since clearing your browser data would otherwise wipe everything.

The notes are permanently unrecoverable. There is no reset, no escrow and no backdoor by design.

Each vault is encrypted with AES-256 in GCM mode, which both encrypts and authenticates, so a wrong passphrase or any tampering simply fails to decrypt. The key is stretched from your passphrase with PBKDF2-HMAC-SHA-256 at 210,000 iterations over a fresh 16-byte random salt, with a random 12-byte IV per encryption, all from the Web Crypto API and crypto.getRandomValues. The cipher is strong, but the weakest link is the passphrase: a short or common one can be brute-forced offline if an attacker obtains the ciphertext, so use a long, unique passphrase.

AES-256-GCM authenticated encryption with a PBKDF2-HMAC-SHA-256 key (210,000 iterations) and a random salt and IV — but its real strength depends on your passphrase.

Use Export to download your vault as a file that stays encrypted with your passphrase, so it is safe to store or transfer. On another device open the tool, choose Import, select the file, and unlock it with the same passphrase. You can also change your passphrase at any time, which re-encrypts the whole vault. Remember that importing replaces the vault currently stored in that browser, and that a shared or compromised computer can expose notes while they are unlocked.

Yes. Export the still-encrypted vault to a file, then import it on another browser and unlock it with the same passphrase.

A 100% client-side encrypted notes vault: one master passphrase unlocks notes encrypted with AES-256-GCM (PBKDF2-HMAC-SHA-256 key, random salt + IV) via the Web Crypto API, with only the ciphertext stored in this browser’s IndexedDB. Create, edit, search, export / import and change-passphrase — nothing is ever uploaded.

Features

Master-passphrase vault: create, edit, delete and search notes in memory
AES-256-GCM encryption with a PBKDF2-HMAC-SHA-256 key (210,000 iterations, random salt + IV)
Only ciphertext is persisted to IndexedDB; Lock wipes plaintext from memory
Export / import the encrypted vault file for backup and moving devices
Change passphrase (re-encrypts), passphrase strength meter, random generator and idle auto-lock

PriceFree

CategorySecurity & Privacy

PlatformAll (any modern browser)

PrivacyNotes are encrypted and decrypted entirely on your device with the Web Crypto API (AES-256-GCM + PBKDF2-HMAC-SHA-256), keys and randomness come from crypto.getRandomValues, and only the ciphertext is stored in this browser’s IndexedDB; there is no server, upload, sync, CDN in the crypto path or telemetry, locking wipes plaintext from memory, the tool works offline once cached, and the only optional network use is consent-gated ads that never see your notes

Input: Master passphrase, Note title + body (typed), Exported vault file (JSON envelope with encrypted payload) for import

Output: Encrypted vault blob in IndexedDB (ciphertext only), Exported encrypted vault file (.json), Decrypted notes shown in memory while unlocked

Detailed Explanation

How It Works

What Secure Notes Is

Secure Notes is a 100% client-side encrypted notepad: a small “vault” of notes that is unlocked by a master passphrase and lives only in your browser. Every note (title and body) is held together in one vault that is serialised to JSON and encrypted as a single authenticated ciphertext blob; only that ciphertext is written to storage, never the plaintext. When you unlock, the blob is decrypted into memory so you can read, search and edit; when you lock, the decrypted notes and the passphrase are cleared from memory. There is no account, no server and no sync — the tool is a private aid, not a cloud service.

A passphrase-unlocked vault of notes, entirely in the browser
Whole vault encrypted as one AES-256-GCM blob; only ciphertext stored
Unlock decrypts into memory; Lock wipes plaintext and passphrase
No account, no server, no sync, no telemetry
A lightweight private notepad, not a full password manager

Methodology

How the Vault Is Encrypted and Stored

On create, you choose a master passphrase and an empty vault is encrypted and saved. The tool derives a 256-bit key from your passphrase with PBKDF2-HMAC-SHA-256 (210,000 iterations) over a fresh random 16-byte salt, then encrypts the vault JSON with AES-256-GCM using a random 12-byte IV; the salt, IV and iteration count are packed with the ciphertext so it is self-describing. That base64 blob is persisted to the browser’s IndexedDB via idb-keyval. Every create, edit or delete re-encrypts the entire vault with a new random IV and rewrites the blob, so what is on disk is always ciphertext. Search runs only on the decrypted notes held in memory while unlocked.

PBKDF2-HMAC-SHA-256, 210,000 iterations, random 16-byte salt
AES-256-GCM with a fresh random 12-byte IV per encryption
Salt, IV and iterations packed with the ciphertext (self-describing)
Persisted to IndexedDB (idb-keyval) as ciphertext only
Every save re-encrypts the whole vault; search is in-memory

Technical Details

The Cryptography in Detail

All cryptography uses the browser’s native Web Crypto API (window.crypto.subtle) and crypto.getRandomValues for every salt, IV and generated passphrase — never Math.random. AES-GCM is authenticated encryption: a 128-bit authentication tag is produced and checked on decrypt, so a wrong passphrase or any tampering with the stored blob simply fails rather than returning garbage. PBKDF2 deliberately makes each passphrase guess expensive, slowing offline brute-force if someone ever obtains the ciphertext. Because the key is derived, not stored, and there is no escrow, the correct passphrase is the only thing that can unlock the vault. Export wraps the same ciphertext in a small JSON envelope; changing the passphrase re-derives a new key and re-encrypts every note.

Web Crypto API + crypto.getRandomValues (never Math.random)
AES-GCM 128-bit tag authenticates data; tampering fails to decrypt
PBKDF2 iterations slow offline brute-force of the passphrase
Key is derived, never stored; no escrow, no backdoor
Change-passphrase re-derives the key and re-encrypts the vault

Limitations

Honest Limitations

This is a lightweight private notepad, not a hardened, audited password manager. The vault lives only in this browser: it is not synced or backed up anywhere, so clearing site data, private-browsing mode, or a browser reset can erase it — export a backup. If you forget the passphrase the notes are unrecoverable; there is no reset. Security depends on your passphrase strength: a short or common one can be brute-forced offline if an attacker obtains the ciphertext. On a shared, public or malware-infected device, notes are visible while unlocked, and any cross-site-scripting flaw in the page could read them in memory; browser storage is only as safe as the device and origin. JavaScript also cannot guarantee decrypted text is fully purged from memory. For high-stakes secrets use a dedicated password manager.

Only in this browser — not synced or backed up; export to keep a copy
Forgotten passphrase = unrecoverable notes (no reset, no escrow)
Strength depends on your passphrase; weak ones are brute-forceable
Shared/compromised device or XSS can expose unlocked notes
Not a substitute for an audited password manager

Privacy & Security

Private by Design

Everything happens on your device. Encryption, decryption, key derivation and random generation run locally through the Web Crypto API; only the ciphertext blob is stored, in this browser’s IndexedDB, and there is no server, upload, sync, CDN in the crypto path, logging or telemetry. Your passphrase is never stored — it exists only in memory to derive the key — and locking clears both the decrypted notes and the passphrase. The tool works offline once cached, supports dark mode and a mobile-first layout, and has no analytics. The only optional network use anywhere on the site is consent-gated ads, which never see your notes or passphrase.

Encrypted/decrypted locally via Web Crypto; only ciphertext stored
Passphrase never stored; Lock wipes plaintext and passphrase from memory
No server, no upload, no sync, no CDN in the crypto path, no telemetry
Works offline once cached; dark-mode and mobile-first
Only optional network use is consent-gated ads that never see your data

Secure Notes — cryptography and storage design
Aspect	Choice	Notes
Cipher	AES-256-GCM	Authenticated; wrong passphrase or tampering fails to decrypt
Key derivation	PBKDF2-HMAC-SHA-256	210,000 iterations over a random 16-byte salt
IV / nonce	Random 12 bytes per encryption	Fresh IV on every save via crypto.getRandomValues
Randomness	crypto.getRandomValues	Never Math.random for salts, IVs or generated passphrases
At rest	Ciphertext in IndexedDB	Plaintext never persisted; exists only in memory while unlocked
Backup	Export / import encrypted file	Stays encrypted; forgotten passphrase = unrecoverable

The cipher is strong; the weakest link is passphrase strength. Notes live only in this browser and are not backed up for you. Everything runs locally. As of July 2026.

Cite This Page

Title: Secure Notes
Author: AnyTool
Published: January 1, 2026
Modified: February 8, 2026
Section: Security & Privacy
URL: https://www.anytool.tech/secure-notes

Formatted Citation

AnyTool. "Secure Notes." AnyTool, January 1, 2026. https://www.anytool.tech/secure-notes

A 100% client-side encrypted notes vault — the /secure-notes route in the AnyTool Security & Privacy category — that stores passphrase-protected notes using real authenticated encryption via the browser’s Web Crypto API, with no server, no upload, no sync and no CDN in the crypto path. A single master passphrase unlocks a vault of notes; on create an empty vault is encrypted and saved, and on unlock the stored blob is decrypted into memory so notes can be listed, searched, created, edited and deleted. The whole vault (every note’s title and body) is serialised to JSON and encrypted as one AES-256-GCM ciphertext, with a 256-bit key derived from the passphrase by PBKDF2-HMAC-SHA-256 at 210,000 iterations over a fresh random 16-byte salt and a random 12-byte IV per encryption (the shared textCryptoEngine packs the version, iteration count, salt and IV with the ciphertext so it is self-describing); every create, edit or delete re-encrypts the entire vault with a new IV and rewrites the blob, which is persisted to the browser’s IndexedDB via idb-keyval, so only ciphertext ever touches storage and search runs only on the decrypted notes in memory. The tool provides export and import of the still-encrypted vault as a JSON envelope for backup and moving between devices, a change-passphrase action that re-derives the key and re-encrypts everything, a passphrase strength meter, a cryptographically-random passphrase generator (crypto.getRandomValues, never Math.random), a Lock button that wipes the decrypted notes and passphrase from memory, and an optional idle auto-lock that re-locks after a chosen interval. The page follows the golden design system with a custom SecureNotesIcon in the header and a feature card, exactly four trust badges, a lock/create-vault screen, an unlocked two-pane vault (searchable note list plus a live editor with word and character counts), three feature cards, a prominent privacy note and an HONEST limitations note, exactly three horizontal ad slots (secure-notes-top / -mid / -bottom) and a sticky mobile action bar, all with full dark-mode and mobile-first responsive support. It is prominently HONEST about its threat model: this is a lightweight private notepad, not a hardened password manager; the vault lives only in this browser and is not synced or backed up, so clearing site data, private mode or a browser reset can erase it and users should export a backup; a forgotten passphrase means the notes are permanently unrecoverable because the key is derived and never stored and there is no escrow or backdoor; the encryption is only as strong as the passphrase, since a short or common one can be brute-forced offline if the ciphertext is obtained; a shared, public or malware-infected device can expose notes while unlocked and any cross-site-scripting flaw in the page could read them in memory; and JavaScript cannot guarantee decrypted text is fully purged from memory. Privacy is structural: encryption, decryption, key derivation and randomness all run locally via the Web Crypto API, only the ciphertext is stored, the passphrase is never persisted, locking clears plaintext and passphrase from memory, the tool works offline once cached, there is no analytics, and the only optional network use is consent-gated ads that never see the notes or passphrase.