ROT13 / ROT47 Encoder & Decoder
Apply ROT13, ROT5 for digits (together ROT18) or ROT47 to printable ASCII. Each is its own inverse, so the same button encodes and decodes. Runs in your browser.
Each of these ciphers is its own inverse — running it again on the output returns the original text.
ROT13 rotates each letter 13 places along the alphabet — a light obfuscation used to hide spoilers and puzzle answers. Because 13 is half of 26, applying it twice gives back the original, so one operation both encodes and decodes. This tool also offers ROT5 for digits (together ROT18) and ROT47 across all printable ASCII.
How to use this tool
- Type or paste your text.
- Choose ROT13, ROT18 (also rotates digits) or ROT47.
- The result updates as you type.
- Run it again on the output to get the original back.
Formula
ROT13 maps a letter at position x to (x + 13) mod 26. ROT47 shifts printable ASCII 33–126 by 47 modulo 94. Both are self-inverse because the shift is exactly half the alphabet size.
Example
"Hello" becomes Uryyb with ROT13, and w6==@ with ROT47.
Frequently asked questions
Is ROT13 secure?
Not at all. It hides text from a casual glance but offers no security — anyone can reverse it instantly. Use it for spoilers and puzzles, never for protecting information.
What is ROT47?
ROT47 rotates all 94 printable ASCII characters, so it also scrambles digits and punctuation, not just letters. It too is its own inverse.
Does ROT13 change numbers or punctuation?
No. Plain ROT13 only moves the letters A–Z. ROT18 also turns each digit five places (0↔5, 1↔6 …), and ROT47 rotates every printable ASCII character from ! to ~, including digits and punctuation.
Why does encoding and decoding use the same button?
Because the shift is half the character range, applying the cipher a second time undoes it. There is no separate decode step.
Last updated:
Page address with these inputs: https://kakao.mobile/tools/rot13-tool/
Cite or embed this tool
kakaoCalc. (2026, November 8). ROT13 / ROT47 Encoder & Decoder. https://kakao.mobile/tools/rot13-tool/
“ROT13 / ROT47 Encoder & Decoder.” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/rot13-tool/.
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