ROT13 Cipher
Encode and decode ROT13, ROT5, ROT18, ROT47, and custom rotations. 100% client-side.
ℹ️ Note: ROT13 is not encryption — it is a simple, reversible substitution cipher used for hiding spoilers and puzzle answers. Never use it to protect secrets.
ROT13: Letters A–Z → N–A (classic)✓ Same operation encodes and decodes
104 chars
104 chars
📖 ROT13 Alphabet Mapping
| Plain | Cipher | Plain | Cipher |
|---|---|---|---|
| A | N | a | n |
| B | O | b | o |
| C | P | c | p |
| D | Q | d | q |
| E | R | e | r |
| F | S | f | s |
| G | T | g | t |
ROT13 is symmetric: applying it twice returns the original. This is why ROT13 has no separate encode/decode operation.
🔒 100% private: All rotation happens in your browser. Your text never leaves your device.
About ROT13 Cipher
ROT13 ("rotate by 13 places") is a simple letter substitution cipher that replaces each letter with the one 13 positions after it in the alphabet: A→N, B→O, ..., N→A, ..., Z→M. Because the English alphabet has 26 letters, applying ROT13 twice returns the original text — the same operation encodes and decodes. ROT13 is NOT encryption — it is trivially reversible and offers no security. Its purpose is to hide text that might spoil a surprise (punchlines, spoilers, puzzle answers) from casual view. ROT5 is the same idea for digits, ROT18 combines ROT13 + ROT5, and ROT47 rotates over 94 printable ASCII characters. This tool supports all four plus any custom rotation.
How It Works
- Choose a rotation: ROT13, ROT5, ROT18, ROT47, or custom (1–25).
- Enter your text — encoding and decoding use the same operation.
- See the rotated output instantly.
- Copy the result or switch rotations.
✨ Key Features
- ✓ROT13 — the classic letter rotation
- ✓ROT5 — digit rotation (0–9)
- ✓ROT18 — ROT13 + ROT5 combined
- ✓ROT47 — rotates over 94 printable ASCII chars
- ✓Custom rotation (ROT1 to ROT25)
- ✓Preserves case (uppercase stays uppercase)
- ✓Preserves punctuation, spaces, and non-Latin characters
- ✓Live conversion as you type
- ✓Handles Unicode and emoji correctly
- ✓100% client-side — no data sent to any server
🎯 Common Use Cases
- →Hiding spoilers, punchlines, or puzzle answers in forums
- →Learning basic substitution ciphers
- →Playing with simple ciphers in CTF challenges
- →Creating puzzles and escape room clues
- →Teaching the concept of rotation ciphers
- →Debugging ROT13-based text transforms
- →Encoding text for fun in chat or comments
- →Comparing ROT13 with Caesar cipher variations
💡 Advanced Tips & Pro Insights
- ▸ROT13 is a special case of the Caesar cipher with shift 13. Because 13 is exactly half of 26, applying ROT13 twice returns the original — hence no separate encode/decode.
- ▸ROT5 rotates digits: 0→5, 1→6, ..., 5→0, ..., 9→4. Used together with ROT13 for ROT18.
- ▸ROT47 rotates over the printable ASCII range (33–126, 94 chars). Because 94/2 = 47, applying ROT47 twice returns the original.
- ▸ROT13 is NOT encryption. It is encoding, and reversible by anyone. Never use it to protect secrets.
- ▸Other ROT values (like ROT8) are the Caesar cipher with that shift. They are NOT self-inverse (you need the opposite shift to decode).
Frequently Asked Questions
Is this ROT13 tool free?▾
Yes, this ROT13 cipher tool is completely free with no signup, email, or usage limits.
Is my data safe?▾
Yes, 100% safe. All rotation happens in your browser. Your text is never uploaded to any server.
What is ROT13?▾
ROT13 is a simple substitution cipher that replaces each letter with the one 13 positions after it in the alphabet (A↔N, B↔O, etc.). Because the alphabet has 26 letters, applying ROT13 twice returns the original.
Why does ROT13 encode and decode with the same operation?▾
Because 13 is exactly half of 26. Rotating by 13 twice is the same as rotating by 26, which is no change. So the same transformation both encodes and decodes.
Is ROT13 encryption?▾
No. ROT13 is trivially reversible — it is not encryption and offers no security. Never use it to protect secrets. It is only for casual obfuscation (spoilers, puzzle answers).
What is ROT5?▾
ROT5 rotates the digits 0–9 by 5 positions (0→5, 1→6, ..., 5→0, ..., 9→4). It is used alongside ROT13 in ROT18 for mixed letter-and-number encoding.
What is ROT18?▾
ROT18 combines ROT13 (letters) and ROT5 (digits). It is not a rotation of 18 in the mathematical sense — it is simply ROT13 + ROT5 applied together.
What is ROT47?▾
ROT47 rotates over the 94 printable ASCII characters (33–126). Because 94/2 = 47, ROT47 is also self-inverse — the same operation encodes and decodes. It covers letters, digits, and punctuation in one pass.