ROT13 Caesar Cipher
Apply ROT13 or any Caesar shift to encode and decode text.
Shift letters to hide or reveal text
A Caesar cipher shifts every letter a fixed number of places through the alphabet; ROT13 is the special case that shifts by 13. This tool applies the shift you choose, and because ROT13 is its own inverse, running ROT13 twice returns the original — handy for hiding spoilers or puzzle answers in plain sight.
For example "Hello" under ROT13 becomes "Uryyb", and applying ROT13 to that gives "Hello" straight back.
Security note and privacy
A Caesar shift is a puzzle, not real encryption — it offers no meaningful security and should never protect sensitive data. The transformation runs entirely in your browser, so whatever you enter stays on your device.
Frequently Asked Questions
Why does ROT13 encode and decode with the same button?
Shifting by 13 twice returns to the start of the 26-letter alphabet, so ROT13 is its own inverse.
Is this secure encryption?
No. A Caesar cipher is a puzzle with no real security — never use it to protect sensitive information.
Is my text uploaded?
No. The shift runs in your browser and nothing is sent to a server.
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