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ROT13 Cipher (ROT5, ROT18, ROT47)

Rotate letters by 13 places (or digits, or any Caesar shift) in one step. Running it twice restores the text.

Processed locally in your browser

Options

Used only with "Custom rotation".

0 chars · 0 lines
The result will appear here.

What is ROT13 Cipher (ROT5, ROT18, ROT47)?

ROT13 replaces each letter with the one 13 places further along the alphabet, so A becomes N and Hello becomes Uryyb. Because the alphabet has 26 letters, applying ROT13 twice returns the original, which is why the same tool encodes and decodes. Forums use it to hide spoilers and punchlines.

The family has cousins: ROT5 rotates digits by 5, ROT18 combines ROT13 with ROT5, and ROT47 rotates all printable ASCII characters (codes 33–126) by 47. A custom option applies any Caesar shift from -25 to 25 to letters, optionally to digits too, and "reverse direction" undoes a shift. Characters outside the rotated range, such as accents and emoji, pass through untouched.

How does it work?

  1. Type or paste the text to transform.
  2. Choose the variant: ROT13, ROT5, ROT18, ROT47 or custom rotation with its amount.
  3. Copy the result. For custom shifts, tick "reverse direction" to decode text encoded with the same amount.

Common use cases

  • Hiding a spoiler or puzzle answer in a forum post or README.
  • Decoding a message that a puzzle, geocache or CTF warm-up says is "ROT13".
  • Teaching how the Caesar cipher and modular arithmetic work.
  • Lightly obscuring an e-mail address or joke so that it is not read at a glance.

Examples

Try this input in the tool above:

Input
Hello, World! Meet at 10:45 — Why did the chicken cross the road?
Output
Uryyb, Jbeyq! Zrrg ng 10:45 — Jul qvq gur puvpxra pebff gur ebnq?

Privacy

ROT13 Cipher (ROT5, ROT18, ROT47) runs entirely in your browser. The text or files you provide are processed on your device and are not uploaded, logged or stored on our servers.

Limitations

ROT ciphers offer no security: anyone can reverse them, and a Caesar shift falls to frequency analysis in seconds. Never use them to protect passwords or private data.

Frequently asked questions

Why does the same tool encode and decode ROT13?

The Latin alphabet has 26 letters and 13 is half of 26, so shifting by 13 twice returns to the start. Custom shifts other than 13 need the "reverse direction" option to decode.

What is ROT47?

It rotates every printable ASCII character from "!" (33) to "~" (126) by 47 positions, so it also scrambles digits and punctuation. It is also its own inverse.

Are accents and non-Latin letters rotated?

No. Only A–Z and a–z (and digits in ROT5/ROT18/ROT47) change. Other characters are copied as they are.

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