ROT13 Encoder/Decoder - Free Online Tool
Encode and decode text using ROT ciphers (ROT5, ROT13, ROT18, ROT47). Simple, symmetric substitution cipher for obfuscating text - perfect for puzzles, forums, and basic privacy.
Input (Plain Text)
Output (Encoded/Decoded)
What is ROT13?
ROT13 ("rotate by 13 places") is a simple letter substitution cipher that replaces each letter with the letter 13 positions after it in the alphabet. It's a special case of the Caesar cipher with a shift of 13, making it symmetric - encoding and decoding use the same operation.
Widely used in online forums, email, and Usenet to hide spoilers, punchlines, puzzle solutions, and potentially offensive content. ROT13 provides no cryptographic security but serves as a simple obfuscation technique requiring deliberate effort to read.
Cipher Variants
- ✓ROT5: Rotates only digits (0-9) by 5 positions
- ✓ROT13: Classic cipher rotating letters (A-Z) by 13 positions
- ✓ROT18: Combination of ROT5 and ROT13 (letters + numbers)
- ✓ROT47: Rotates all printable ASCII characters (33-126)
- ✓Custom: Choose any rotation from ROT1 to ROT25
How to Use ROT13 Encoder/Decoder
Enter Your Text
Type or paste plain text to encode, or ROT-encoded text to decode. The cipher is symmetric, so the same operation works both ways.
Select Cipher Type
Choose from ROT5, ROT13, ROT18, ROT47, or set a custom rotation (1-25). Each cipher affects different character sets.
Copy or Download
View results instantly in live mode. Copy to clipboard, download as file, or swap to reverse the operation.
Common Use Cases
Online Forums & Communities
Hide spoilers for movies, TV shows, books, and games. Share puzzle solutions without immediately revealing answers to others.
Email & Messages
Obscure punchlines, sensitive information, or content that requires deliberate effort to read. Common in mailing lists and Usenet.
Geocaching & Puzzles
Encode clues, coordinates, and hints for treasure hunts, escape rooms, and puzzle games requiring participants to decode messages.
Educational & Training
Teach cryptography basics, demonstrate substitution ciphers, and introduce students to encoding concepts in computer science courses.
Encoding Examples
⚠️ Important Note: ROT ciphers provide NO cryptographic security. They are symmetric and trivial to break. Use only for obfuscation, not for protecting sensitive data.