The Language Cipher transforms text into another writing system, optionally protected by a secret key:

Choose an output script - Chinese hanzi, English letters, Greek, Cyrillic, Thai or Japanese kana.
Encrypt - every character is encoded into script characters (1 hanzi or 2 letters per byte).
Secret key (optional) - set a key to scramble the encoding; the same key is then required to decrypt.
Decrypt - paste the ciphertext, pick the same language and key, and the original text is restored.

The encoding is fully reversible: text → UTF-8 bytes → script characters. With a key, each byte is shifted by the key characters (mod 256) before encoding, and unshifted again on decryption. A wrong key or language produces an error or unreadable text, so keep both consistent.

All conversion happens locally in your browser - nothing is sent to a server.