UsefulTab
Text Encrypt / Decrypt
Passphrase-encrypt text with AES-GCM.
Encrypt or decrypt text with a passphrase
Pick a mode, enter your text and a passphrase, then run. The key is derived with PBKDF2 and the text is sealed with AES-256-GCM — all in your browser, nothing uploaded.
Runs entirely in your browserEncrypt text with a passphrase, locally
Type or paste text, choose a passphrase, and this tool encrypts it with AES-256 in GCM mode — an authenticated cipher, so decryption fails cleanly if the passphrase is wrong or the data was altered. The key is stretched from your passphrase with PBKDF2 (SHA-256, 150,000 iterations) over a fresh random 16-byte salt, and every message uses a new random 12-byte IV. The salt and IV are packed in front of the ciphertext and the whole payload is shown as Base64 (or hex), so decrypting later only needs the same passphrase. Everything runs in your browser with the Web Crypto API, so neither your text nor your passphrase is ever uploaded. This offers only AES-GCM — the browser's crypto has no TripleDES or Rabbit cipher.
Common questions
What cipher does this use?
AES-256 in GCM mode, an authenticated encryption cipher from the Web Crypto API. The key is derived from your passphrase with PBKDF2 (SHA-256, 150,000 iterations) using a random 16-byte salt, and each message uses a random 12-byte IV. There is no TripleDES or Rabbit option — the browser's SubtleCrypto does not provide them, so only AES-GCM is offered.
What is in the Base64 (or hex) output?
The salt (16 bytes), then the IV (12 bytes), then the AES-GCM ciphertext with its authentication tag, concatenated and encoded. Decrypting reads the salt and IV from the front, so you only need to keep the output string and the passphrase.
What happens if I enter the wrong passphrase?
Decryption fails cleanly with a clear message. GCM verifies an authentication tag, so a wrong passphrase (or any tampering with the data) is detected and no garbage plaintext is returned.
Can I decrypt this somewhere else?
Yes, as long as the other side implements the same scheme: PBKDF2-SHA256 (150k iterations) over the leading 16-byte salt to derive a 256-bit AES-GCM key, then AES-GCM with the following 12-byte IV over the remaining ciphertext. Use the Base64 output and parse those fixed-length prefixes.
Is my text or passphrase uploaded?
No. All key derivation and encryption run in your browser tab with the Web Crypto API. Nothing you type is sent to a server, which is also why it works offline.