letter substitution · spoiler-hiding · not security
Rotates letters by a fixed amount around the alphabet. ROT13 (shift 13) is self-inverse. Used for hiding spoilers, puzzles, and trivia — not cryptography. Choose your shift below.
Input text box — the rotated result appears instantly in Rotated text.Shift slider (from 1 to 25) to choose how far letters rotate — the heading updates to match.ROT1, ROT5, ROT13, ROT18, or ROT25 — to jump to a common shift.Copy result to copy the rotated text to your clipboard.Clear any time to reset the input and start over.ROT13 is the long-standing convention for hiding spoilers, punchlines, and answers in forums, comments, and mailing lists. Rotate, share, and let readers decode it themselves.
Escape rooms, scavenger hunts, CTF challenges, and puzzle caches often hide messages with a Caesar shift. Paste the ciphertext and sweep the slider to crack it.
Caesar rotation is the simplest substitution cipher there is — perfect for demonstrating how a plaintext alphabet maps to a ciphertext alphabet.
Watch what happens when a rotation pushes a letter past Z: it wraps back to A. A quick, visual way to understand modular arithmetic.
A fast way to scramble text for fun, while making clear why rotation alone is no substitute for real encryption.
Everything runs in your browser. Nothing is uploaded, logged, or sent to a server — safe for text you'd rather not share.
A Caesar cipher shifts each letter a fixed number of positions through the alphabet. ROT13 is the special case with a shift of 13, making it self-inverse: applying it twice returns the original text.
No. There are only 25 possible shifts, so rotation is trivially reversible. It's obfuscation for hiding spoilers and solving puzzles — not protection for sensitive data.
Because 13 + 13 = 26, a full lap of the alphabet. Rotating every letter by 13 twice lands it right back where it started.
Letters (A–Z and a–z) rotate by the shift, and digits (0–9) rotate by the shift modulo 10. Everything else — spaces, punctuation, symbols — passes through unchanged, and letter case is preserved.
They're shortcuts that set the Shift slider to 5, 13, 18, or 25. Since the same shift applies to letters and digits, digits move by that amount modulo 10 — for example, under ROT13 digits shift by 3.
Yes. Uppercase and lowercase letters rotate within their own ranges, so Hello becomes Uryyb under ROT13 — capitalization is untouched.
Never. All rotation happens locally in JavaScript. Your input is not sent to, stored on, or logged by any server.