What Is Caesar Cipher?

A free online Caesar cipher tool for encrypting and decrypting text. Supports custom shift values (1-25), quick ROT presets (ROT3, ROT5, ROT13, ROT47), and a brute-force mode that displays all 25 possible shifts simultaneously for cracking unknown shifts. Includes letter frequency analysis to help identify the correct decryption. Non-alphabetic characters are preserved, and case is maintained. The Caesar cipher is a classic monoalphabetic substitution cipher used by Julius Caesar for private correspondence.

Why Use Caesar Cipher?

  • Custom shift (1-25) with slider and quick ROT buttons (ROT3, ROT5, ROT13, ROT47)
  • Brute-force mode shows all 25 shifts at once
  • Letter frequency analysis with visual bar chart
  • Preserves non-alphabetic characters and case
  • Professional-grade modular arithmetic implementation

How to Use Caesar Cipher — Step by Step

1

Enter your text in the input box.

2

Choose Encrypt or Decrypt mode.

3

Adjust the shift value with the slider or click a ROT preset button.

4

Toggle "All" to brute-force all 25 shifts.

5

Use the letter frequency chart to help identify the correct shift.

Who Is Caesar Cipher Best For?

  • students learning cryptography
  • CTF players
  • puzzle solvers
  • cryptography enthusiasts

Caesar Cipher — Frequently Asked Questions

What is the difference between ROT13 and Caesar cipher?

ROT13 is a Caesar cipher with shift 13. Since the alphabet has 26 letters, ROT13 is self-inverse — applying it twice returns the original text. ROT47 extends the concept to all 94 printable ASCII characters.

Can the Caesar cipher be cracked?

Yes, easily. There are only 25 possible shifts, so brute-force reveals all of them instantly. The frequency analysis chart helps identify which shift produces the most natural letter distribution.

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Free online tool — works in your browser, no sign-up required. Start using it right now.

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