Cipher Encoder

Encode or decode text using Caesar cipher, ROT13 and Atbash — classic substitution ciphers.

Instant result Runs in browser

Tip: ROT13 and Atbash are self-inverse — applying the same operation twice returns the original text.

Alphabet Table

Plain A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Cipher A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Caesar (shift 3)
A→D · B→E · ... · Z→C

How to use?

  1. 1
    Choose a cipherSelect Caesar, ROT13 or Atbash. For Caesar, adjust the shift amount with the slider.
  2. 2
    Enter your textType in the input field; the encoded (or decoded) text appears instantly.
  3. 3
    Copy or swapCopy the result. Use "Swap Fields" to move encoded text to input and decode it.

FAQ

What is the Caesar cipher?
One of the oldest known encryption methods, used by Julius Caesar in his military dispatches (58–50 BC). Each letter is shifted forward by N positions in the alphabet. With shift 3: A→D, B→E, Z→C. To decode, shift backward by the same amount.
What is ROT13 and where is it used?
ROT13 is a Caesar cipher with shift 13. Because the Latin alphabet has 26 letters (13+13=26), the same operation both encodes and decodes. It became standard on Usenet for hiding spoilers, and is still used today for basic obfuscation.
What is the Atbash cipher?
Atbash reverses the alphabet: A↔Z, B↔Y, C↔X. Named from Hebrew letters (aleph-beth-shin), it appears in Old Testament texts from the 6th century BC. Like ROT13, it is self-inverse — encoding twice returns the original.

Classic Substitution Ciphers

Caesar, ROT13 and Atbash belong to the family of substitution ciphers — each letter is systematically replaced by another according to a fixed rule. They form the historical foundation of cryptography.

Caesar Cipher

Each letter is shifted by N positions. With shift 3 (the classic): A→D, B→E, Z→C. To decode, shift backwards. Julius Caesar used shift 3; Augustus Caesar used shift 1.

ROT13

A Caesar cipher with shift exactly 13, meaning encoding and decoding are the same operation. Widely used on Usenet and online forums to hide spoilers and puzzle answers.

Atbash

Reverses the alphabet (A↔Z). Found in Hebrew scripture dating to 600 BC. When applied to Latin letters: A=Z, B=Y, C=X… Z=A. Applying it twice returns the original text.

Cryptographic Security

These ciphers offer no modern cryptographic security. With only 26 possible shifts (Caesar) or fixed mappings (ROT13, Atbash), they can be broken instantly by brute force or frequency analysis. Use them for education, games and puzzles — not for protecting sensitive data.

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