Caesar Cipher
Encode and decode Caesar and ROT13 shift ciphers with a custom shift value. Letters are shifted through the alphabet while numbers and symbols stay untouched. Runs entirely in your browser.
About Caesar & ROT13 Ciphers
Caesar and ROT13 are shift ciphers that replace each letter with one N positions away. They are weak and only good for puzzles, not security. For real encryption use theText Encryption tool.
Secure & Private Client-Side
This tool runs entirely in your browser. No data is sent to any server, ensuring your information remains private and secure.
About Caesar Cipher
Encode and decode Caesar and ROT13 shift ciphers with a custom shift value. Letters are shifted through the alphabet while numbers and symbols stay untouched. Runs entirely in your browser.
Frequently Asked Questions
What is the difference between ROT13 and Caesar cipher? expand_more
ROT13 is a Caesar cipher with a fixed shift of 13. Because the alphabet has 26 letters, applying ROT13 twice returns the original text.
How do I decode a Caesar cipher without knowing the shift? expand_more
Try every shift from 1 to 25 until the output reads as plain English. The Custom preset lets you change the shift in one click.
Are numbers and punctuation shifted? expand_more
No. Only A-Z and a-z are shifted; digits, punctuation, and whitespace pass through unchanged.
Is the Caesar cipher secure? expand_more
No. Shift ciphers are trivially broken by frequency analysis and brute force. Use the [Text Encryption](/tools/text-encryption/) tool for real AES encryption.
Does anything leave my browser? expand_more
No. All encoding and decoding happens locally.
Common Use Cases
- Geocaching & CTFs: Quickly decode ROT13 or Caesar-shifted hints hidden in puzzles.
- Spoiler Tags: ROT13 a plot twist or answer so it is not readable at a glance.
- Classroom Crypto: Demonstrate classical ciphers when teaching the history of cryptography.
- Obfuscation: Lightly disguise text such as puzzle answers without affecting non-letter characters.