Caesar Cipher Decoder
Reverse a Caesar shift by N positions.
How to Use
- Type or paste your input on the left.
- The result appears live on the right - no buttons needed.
- Copy the output with one click.
About this codec
Reverse a Caesar shift by N positions.
About Caesar cipher
Caesar cipher is a shift cipher that rotates each letter by a fixed amount (ROT13 is a shift of 13). This tool lets you decode Caesar cipher instantly and entirely in your browser. It is commonly used for puzzles, light obfuscation, and teaching cryptography basics.
ABC → DEF with a shift of 3; with ROT13, HELLO → URYYBHow to use it
Type or paste the Caesar cipher you want to read into the box and it turns into normal text live as you type — everything runs locally in your browser. Learn more in the Knowledge Base.
Frequently Asked Questions
Does this leave my browser?
No - the conversion runs entirely in JavaScript on this page.
What does Caesar cipher look like?
ABC becomes DEF with a shift of 3; with ROT13, HELLO becomes URYYB. Caesar cipher is typically used for puzzles, light obfuscation, and teaching cryptography basics.
Does my text leave my browser?
No. The Caesar cipher conversion runs entirely in JavaScript on this page — nothing is uploaded, and it works offline.
Is Caesar cipher secure?
No — Caesar cipher is a classical cipher that is easy to break. Use it for puzzles and learning, and use real encryption when you actually need confidentiality.
Common Use Cases
Puzzles, light obfuscation, and teaching cryptography basics
Caesar cipher is commonly used for puzzles, light obfuscation, and teaching cryptography basics — decode it here in one step.
Learning & puzzles
See how text maps to Caesar cipher — handy for coursework, CTF challenges, and puzzle hunts.
Private by design
Everything runs locally in your browser, so you can paste sensitive text without it leaving your device.
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