ROT13 / Caesar Cipher
What is a ROT13 / Caesar Cipher?
Encode and decode text using ROT13 (Rotate 13 places) and Caesar cipher substitution algorithms. Customize shift key amounts (1 to 25) and view an instant 25-shift brute-force decryption table.
Why Use This Tool?
- Geocaching & Puzzle Solving: Decode ROT13 hints and spoiler text on geocaching sites and online puzzle forums.
- Cybersecurity & CTF Challenges: Crack classic substitution ciphers during Capture The Flag (CTF) security competitions.
- Educational Cryptography: Learn the fundamentals of historical monoalphabetic substitution ciphers.
How to Use
- Enter or paste text into the input box.
- Select Shift Key (default: ROT13 = 13 shift places).
- Inspect encoded text or view the 25-shift brute-force decryption table.
Real Working Example
Input:
Text: "Uryyb JBEYQ!" | Shift: 13 (ROT13)
Output Result:
Decoded Text: "Hello WORLD!"
Important Technical Details & Security Standards
- Alphabet Shift Algorithm: Shifts ASCII uppercase (A-Z) and lowercase (a-z) letters while preserving numbers and punctuation.
- Full 25-Shift Brute-Force Output: Displays all 25 possible Caesar cipher rotations simultaneously for instant ciphertext cracking.
- Local Memory Execution: Fast in-browser processing.
Related Security & Crypto Tools
- Vigenère Cipher: Polyalphabetic substitution cipher.
- Base64 Encoder/Decoder: Encode Base64 text.
- Encrypt / Decrypt Text: Encrypt text with AES-256.
Frequently Asked Questions
What is ROT13?
ROT13 is a special case of the Caesar cipher that rotates letters by 13 positions (A becomes N, B becomes O). Applying ROT13 twice restores original text.
Why is ROT13 commonly used in forums and games?
ROT13 is used to hide spoilers, puzzle answers, and joke punchlines from casual glance without real encryption.
Is the Caesar cipher secure for real data?
No, the Caesar cipher has only 25 possible shifts and can be cracked in milliseconds by brute force or frequency analysis.
Is it free?
Yes, 100% free.
Does ROT13 change numbers or punctuation?
No, standard ROT13 shifts only alphabetic letters (A-Z, a-z), keeping numbers and symbols unchanged.
Is my text stored on a server?
No, all encoding and decoding runs 100% locally in your web browser.