About SealBox

SealBox is a hub of encryption tools — a file encryptor that password-protects any file, a text encryptor that turns messages into shareable ciphertext, an explicit AES bench with your own key and IV, an RSA keypair generator with PEM export, and a PBKDF2 key deriver. Every operation runs entirely in your browser. Runs in your browser — your files and secrets never leave your device.

Uploading a file to encrypt it defeats the point

Many incumbent online encryptors take a server upload of the very file you are trying to keep secret — you have to trust them with the plaintext. SealBox takes the opposite approach: the file or text is read into your browser's memory, encrypted there by the browser's own audited Web Crypto implementation, and written back out as a download. There is no backend, no upload, and no network request involved in any operation — you can verify this yourself in the DevTools Network tab.

What runs under the hood

Files and text use AES-256-GCM — authenticated encryption, so decryption verifies an integrity tag and tampered input is rejected rather than decrypted to garbage. The 256-bit key is derived from your password with PBKDF2-HMAC-SHA256 at 600,000 iterations (OWASP 2023 guidance) and a random 16-byte salt; a fresh random 12-byte IV is drawn for every single encryption. RSA keys are generated by Web Crypto's own RSA-OAEP implementation and exported as standard PEM. We say what it is — browser-local AES-256-GCM — and nothing grander.

A forgotten password is unrecoverable — by design

There is no reset link, no recovery copy, and no backdoor, because your password never leaves your device and the key is never stored. If you lose the password, the data is gone. That is what real encryption means — treat it as a feature, and keep a copy of the password somewhere safe (a password manager is a good pairing).

Free tier vs Pro

The core tools are free and fully functional with no limits: single-file and single-text encryption (any size your browser can hold in memory), the AES bench, RSA keypair generation, and PBKDF2 derivation — all unlimited, no signup. SealBox Pro adds paid conveniences on top — bulk file encryption(many files sealed into one .sealbox archive with a single password), an encrypted-notes vault(master-password notes stored on your device), custom encryption presets (PBKDF2 iterations, AES-128 vs 256, output format), and an ad-free experience. It is a one-time license; the free single-item encryption stays free forever.

Browse the tools

• File Encryption

  Password-protect any file with AES-256-GCM before you share it.

• Text Encryption

  Encrypt messages into shareable ciphertext strings and back.

• Keys & Derivation

  A raw AES bench, RSA keypair generation with PEM export, and PBKDF2 derivation.