Caesar Cipher / ROT13 Tool
Encode or decode text with a Caesar shift cipher, including the classic ROT13.
Encoded (shift +3)
Phhw ph dw plgqljkw.
Decoded (shift -3)
Jbbq jb xq jfakfdeq.
ROT13 is just a Caesar cipher with a shift of 13 — applying it twice gets you back the original text. Everything runs in your browser.
Frequently asked questions
What is a Caesar cipher?+
One of the oldest known ciphers — each letter is shifted a fixed number of places through the alphabet (wrapping from Z back to A). Numbers, spaces, and punctuation are left unchanged.
What makes ROT13 special?+
ROT13 is a Caesar cipher with a shift of exactly 13 — since the alphabet has 26 letters, applying the same ROT13 transformation twice returns the original text.
Is this secure encryption?+
No — a Caesar cipher is trivially easy to break and offers no real security. It's meant for puzzles, obscuring spoilers, or as a teaching example, not protecting sensitive information.