Text · secret alphabetsClassical Ciphers

Paste the ciphertext into “Identify the cipher” at the top of the page. We try every key-free cipher we know — Caesar with all shifts, Atbash, ROT13, A1Z26, the Polybius square and the Bacon cipher — compare the results with a dictionary and show the three that look most like real text. Dots and dashes are recognised as Morse code and sent to its decoder.

The Caesar cipher has its own page with every shift tried and a printable wheel, and the Vigenère cipher has one with the key found from the text. Atbash, ROT13 and ROT47, A1Z26, the Polybius square, the scytale, the rail fence and the Bacon cipher have their own pages too, where you can encode, decode and see a diagram. The Enigma machine is a simulator with lamps and the signal path. Playfair and simple substitution are on the way.

A cipher hides the meaning: without the key or the rule the text cannot be read, and the key is kept secret. A code just writes the same letters with other signs so they are easy to transmit, and its table is public — that is how Morse code and Braille work. That is why Morse is a separate tool on this site rather than a cipher.

For children aged 7–10, A1Z26 and Atbash work well: no key is needed, a sheet of paper and a pencil are enough. For older players, the Caesar cipher with a number or a printed cipher wheel as the hint. For a hard quest, Vigenère with a keyword hidden in another riddle. If the message is tapped or flashed, use Morse code. More in the “Which cipher to pick” table.

Yes. The Russian alphabet comes in two versions — 33 letters with Ё and 32 without it — and they give different results: with a shift of 1, “е” becomes “ё” in the first and “ж” in the second. When decoding we try both and show the better one. If the ciphertext contains “ё”, it was encrypted with the 33-letter alphabet, so the other drops out on its own.

No: the search, the dictionary and the scoring all run in your browser, and the text is neither sent to a server nor stored. The dictionary is loaded onto the page as a whole, so it does not reveal what you were looking for. Text gets into a link only if you press “Share” on a cipher page — the button says so right next to it.