Caesar Cipher & ROT13
Encode or decode text with any shift value. ROT13 is shift 13 — click it twice to get back the original.
Previewing input text across all 25 possible shift variations simultaneously:
About Caesar Cipher & ROT13
Learn how substitution ciphers work and why ROT13 is a staple of classical cryptography.
The Caesar Cipher is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is shifted a certain number of places down the alphabet.
ROT13 (rotate by 13 places) is a specific implementation of the Caesar cipher using a shift value of 13. Because the English alphabet has 26 letters, ROT13 is its own inverse—applying the transformation twice returns the original text, making it popular for obscuring spoilers or puzzle solutions.
Any Shift Value
Choose any numeric shift between 1 and 25 to fully customize your encryption key.
Symmetric ROT13
Instantly apply shift 13 where encoding and decoding use the exact same operation.
Encode & Decode
Easily toggle between encryption and decryption modes for any shift key.
Real-Time Translation
See your text transform instantly as you type without needing to click any extra buttons.
Preserves Case & Symbols
Spaces, numbers, punctuation, and uppercase/lowercase casing are correctly maintained.
All-Shift Brute-Force
Preview results across all possible shift combinations simultaneously to easily crack hidden messages.