Cipher Tool

Cipher Tool brings four classic ciphers into one place: ROT13, Caesar shift, Atbash and Vigenère. Choose a cipher, type your text, and encode or decode it in one click. Capital letters stay capital and anything that is not a letter, such as numbers, spaces and punctuation, passes through unchanged.

Each cipher works differently. ROT13 shifts every letter by 13 places and Atbash maps A to Z, B to Y and so on, so both are their own inverse: applying them twice gives back the original. Caesar lets you choose a shift from 1 to 25, and Vigenère uses a keyword to change the shift letter by letter, which is why decoding needs the same keyword that was used to encode.

A short explanation of the selected cipher sits beside the output, which makes the tool handy for classes and for capture-the-flag challenges. To crack an unknown Caesar message, step through the shifts until a readable line appears.

These ciphers are for learning, puzzles and lightly hiding spoilers or answer keys, not for protecting anything sensitive: every one of them can be broken in seconds. The conversion runs in your browser.