Decrypt Text Online

The Text Decrypter in this tool is a browser-based utility that takes an encrypted string (ciphertext) and converts it back into its original readable message (plaintext). It uses the Web Crypto API with AES-256 encryption standards, meaning decryption is done entirely on your device — no servers involved.

You’d decrypt text when you need to read a message or piece of data that was previously encrypted for secure storage or transmission. Common reasons include retrieving a securely stored password or note, reading a private message sent by someone using the Encrypt tab, or recovering your own encrypted data after storing it safely. Since the encryption is strong (AES-256), the only way to get the original text back is through this decryption process with the correct password.

There are four interactive controls in the Decrypt panel. The Clear button (top right of the text area) wipes the input field so you can start fresh. The eye toggle next to the password field shows or hides your password as you type. The Decrypt button at the bottom triggers the decryption process — it derives your key, unpacks the encrypted data, and outputs the original message. The Copy button in the output area copies the decrypted plaintext to your clipboard with one click.

Since this tool works with text pasted directly into a textarea, it’s best suited for text-length content — messages, notes, credentials, and similar strings. There’s no hard limit enforced in the code, but very large inputs may slow down the browser since everything runs in-memory on the client side. It is not designed for binary files or documents; those would need a file-based encryption tool instead.

When you hit Decrypt, the tool first decodes your input from Base64 (or hex) back into raw bytes. It then reads a packed header embedded in those bytes: a flag byte identifies which algorithm was used (AES-GCM or AES-CBC), followed by a 16-byte salt and an IV (initialization vector). Using your password and the extracted salt, it runs PBKDF2 with 100,000 iterations and SHA-256 to re-derive the exact same AES-256 key that was used during encryption. It then passes the key, IV, and remaining ciphertext bytes to the browser’s crypto.subtle.decrypt() function. If the password is correct, it returns the original plaintext. If the password is wrong or the data is corrupted, AES-GCM’s authentication tag will cause the operation to fail and you’ll see a “Wrong password or corrupted data” error.

Completely. It’s a single HTML file that runs entirely in your browser with no account, no backend, no telemetry, and no cost. You can save it to your desktop and use it offline indefinitely.