Caesar Cipher / ROT13

Classic substitution cipher with adjustable shift. Encrypt and decrypt text.

Shift Amount: 13

125

Input

Output

Shift Table

A → N

B → O

C → P

D → Q

E → R

F → S

G → T

H → U

I → V

J → W

K → X

L → Y

M → Z

N → A

O → B

P → C

Q → D

R → E

S → F

T → G

U → H

V → I

W → J

X → K

Y → L

Z → M

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What is this tool?

Caesar cipher and ROT13 encoder/decoder for classical text encryption. The Caesar cipher shifts each letter in the alphabet by a fixed number of positions. ROT13 is a special case with a shift of 13 (applying it twice returns the original text). Used for education, puzzles, and basic text obfuscation—not for real security.

How to use

1
Enter text
Type or paste the text you want to encrypt or decrypt.
2
Set shift value
Choose shift amount (1-25) or select ROT13 preset (shift 13).
3
Get result
The encoded or decoded text appears instantly.

Frequently Asked Questions

What is ROT13?

ROT13 is a Caesar cipher with a fixed shift of 13 positions. Since the English alphabet has 26 letters, applying ROT13 twice returns the original text (13+13=26). Commonly used on forums to hide spoilers or puzzle answers, not for security.

Is Caesar cipher secure?

No. Caesar cipher has only 25 possible keys and can be broken instantly by brute force or frequency analysis. It should never be used to protect sensitive information.

What encryption standard is used?

The tool implements standard algorithms as defined by NIST. For production security use well-tested libraries.