ROT13 & Caesar Cipher
Classic letter-shift ciphers, with brute force.
ROT13 & Caesar Cipher shifts letters by any amount from 1 to 25, with ROT13 as the self-inverse special case, and can brute-force an unknown shift by showing all 25 possibilities at once. It also does Atbash. These are puzzles and obfuscation, explicitly not security. The shifting happens in your browser.
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Runs entirely on your device. No file or text you enter here is uploaded. How to verify it.
How to use ROT13 & Caesar Cipher
- Paste your text.
- Choose ROT13, a custom shift, or Atbash.
- Read the result, or scan all 25 shifts to crack an unknown one.
Questions about ROT13 & Caesar Cipher
Is this encryption?
No. A Caesar cipher has 25 possible keys and is broken by trying all of them, which this page does in one click. It hides a spoiler or a puzzle answer from a casual glance; it protects nothing from anyone who is looking.
Why is ROT13 special?
Because 13 is half of 26, applying it twice returns the original text. That self-inverse property is why Usenet used it for spoilers with a single command in both directions.
What about numbers and punctuation?
Left unchanged by default, with an optional ROT47 mode that shifts the whole printable ASCII range including digits and symbols.
Can it crack a message when I do not know the shift?
Yes, for a Caesar cipher. All 25 shifts are laid out at once and the readable line stands out immediately. That is the whole weakness of the cipher — a keyspace small enough to exhaust by eye.
Does it handle accented letters or other alphabets?
Shifting applies to the 26 Latin letters, A to Z. Accented characters, Cyrillic and Greek pass through unchanged, because a Caesar shift is defined over one 26-letter alphabet and stretching it elsewhere would not round-trip.
Is ROT13 & Caesar Cipher really free, with no limits?
Yes. There is no account, no daily cap, no file-size tier and no watermark, because there is no server cost to recover. The site is funded by clearly disclosed partner recommendations on the Partners page, never by metering the tools.
Are my files or text uploaded when I use ROT13 & Caesar Cipher?
No. Everything is processed by JavaScript running in your browser, on your device. You can verify it: open your browser's developer tools, switch to the Network tab, and use the tool. You will see no request carrying your data — because there is nowhere for it to go.