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ROT13 Encoder online

Encode and decode text with ROT13, ROT5, and ROT47 substitution ciphers

ROT13 Encoder / Decoder logo
by
CHUNKY
MUNSTER
// Input text
// Output (same for encode and decode)

How to Use the ROT13 Encoder / Decoder

  1. Paste the text you want to rotate into the input field.
  2. Pick the variant: ROT13 (letters), ROT5 (digits), or ROT47 (printable ASCII).
  3. The output appears live as you type — no Run button needed.
  4. Apply the same operation again to decode (it's symmetric).

ROT13 is the textbook example of a Caesar cipher with a fixed shift of 13. Because the Latin alphabet has 26 letters, applying the rotation twice returns the original text, which is why the same button on this page handles both encode and decode. ROT5 does the same trick for digits, and ROT47 extends it to the full printable ASCII range so symbols like ! @ # are also scrambled.

How the ROT13 Encoder / Decoder Works

None of these are encryption in any meaningful sense — they're obfuscation, useful for hiding spoilers, puzzle answers, or test data from casual readers. Anything that needs to stay private should go through AES, not ROT.

Frequently Asked Questions

Is ROT13 actually encryption?

No — it offers no real security. The original Usenet use case was hiding spoilers and punchlines, not protecting secrets. The cipher is symmetric and the key is published, so anyone can decode it instantly.

Why is ROT13 self-inverse but ROT47 also is?

Both rotate by exactly half of the alphabet they cover (13 of 26 letters, 47 of 94 printable ASCII characters). Two rotations of half a cycle wrap all the way around, so encode and decode are the same operation.

What does ROT5 do that ROT13 doesn't?

ROT5 only touches digits 0–9 (5 ↔ 0, 6 ↔ 1, etc.) and leaves letters alone. Combine ROT13 + ROT5 ("ROT18") and you get a single pass that obfuscates both letters and digits.

Does ROT47 break Unicode?

It only operates on bytes 33–126 (printable ASCII). Anything outside that range — accented letters, emoji, CJK characters — passes through unchanged, so a paragraph of mixed scripts will be partially rotated.

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