ROT Cipher / Caesar

Apply a Caesar-style rotation to your text. Pick a mode (letters, digits, alnum, or all printable ASCII), set a shift, and the result updates as you type. One-click presets for the three famous variants: ROT5, ROT13, and ROT47. Encoding and decoding are the same operation — apply the same shift again to undo it. Nothing leaves your browser.

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Presets:
Output 
 
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 Reference — what each mode rotates 
  
ModeCharacters affectedModulusFamous preset
   
 letters A–Z, a–z (case preserved) 26 ROT13 (shift 13) 
 
 digits 0–9 10 ROT5 (shift 5) 
 
 alnum A–Z, a–z, 0–9 (case preserved) 26 letters, 10 digits — 
 
 ascii47 ! through ~ (94 chars) 94 ROT47 (shift 47) 
  
 

Every character outside the active mode (whitespace,
      punctuation, accented letters, emoji, CJK, etc.) is preserved
      unchanged. Encoding and decoding use the same call —
      a Caesar cipher is its own inverse when the shift is half
      the modulus (ROT13, ROT5, ROT47) or a multiple of it
      (ROT26 = identity, ROT0 = identity). Otherwise, flip the
      sign of the shift to undo it.

 
 

Pure client-side, works offline once loaded, no upload, no
    tracking. Built on the standard shift-and-wrap alphabet
    trick; not cryptography — this is for puzzles, ASCII
    art, obscuring spoilers, and the occasional dad joke.