Shift letters through the alphabet to encode or decode a Caesar cipher, run the classic ROT13, or rotate all printable ASCII with ROT47. If you do not know the shift, the brute-force table decodes your text under all 26 shifts and highlights the one that scores most English-like. Case is preserved and anything that is not a letter passes through untouched. Everything runs locally in your browser. These are classic ciphers — fun puzzles and light obfuscation, not encryption: for that use AES Encrypt / Decrypt. For more character-level conversions try Morse Code Translator, XOR Cipher, or Base64 Encode / Decode.
ROT13 & Caesar Cipher
Encode and decode ROT13, any Caesar shift, and ROT47 — with a brute-force cracker
Cipher
Direction
ROT13 shifts letters by 13 — exactly half the alphabet — so it is its own inverse: encode and decode are the same operation. Digits, punctuation and spaces are left untouched.
Result will appear here…Frequently asked questions
Is ROT13 or a Caesar cipher actually encryption?
No. There are only 25 useful Caesar shifts, so anyone can try all of them in a second — this tool does exactly that with its "show all 26 shifts" table. ROT13 is weaker still, because the shift is fixed and public. Treat these as puzzles, spoiler hiding, and light obfuscation, never as protection. If you need real confidentiality, use the AES Encrypt / Decrypt tool, which does AES-256-GCM with a password-derived key.
What is the difference between ROT13, a Caesar shift, and ROT47?
A Caesar shift moves each letter a chosen number of positions through the alphabet (A→D for shift 3), leaving digits, punctuation, spaces, and non-Latin characters untouched, and preserving upper and lower case. ROT13 is simply the Caesar shift of 13: because 13 is half of 26, encoding and decoding are the same operation. ROT47 works on the 94 printable ASCII characters from "!" (33) through "~" (126) and rotates them by 47, so it also scrambles digits and punctuation — and, like ROT13, it is its own inverse.
How do I decode a Caesar cipher when I do not know the shift?
Click "Show all 26 shifts". The tool decodes your text under every possible shift and scores each result for how English-like it looks: it counts common English words (each hit is worth a fixed bonus) and subtracts a chi-square distance between the text's letter frequencies and standard English letter frequencies. The highest-scoring row is highlighted as the best guess. It is a ranking heuristic, not a language detector — very short messages, names, or text that is not English can put the real answer in a different row, so scan the neighbouring rows too.
Do I need to pick encode or decode separately?
For ROT13 and ROT47, no — they are their own inverse, so one button does both. For any other Caesar shift the direction matters: encoding with shift N is undone by shifting back N (which is the same as shifting forward 26 − N), and the Direction toggle does that for you. Everything runs in your browser with plain JavaScript; the text you type is never uploaded anywhere.
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