Encoders / Decoders
ROT13 / Caesar Cipher
Rotate letters by 13 (or any shift) - the classic substitution cipher.
Input
Output
Output will appear here
About this tool
ROT13 shifts each letter by 13 places (its own inverse). The general Caesar cipher lets you shift by any amount. Used for spoiler hiding and as a teaching example - it is NOT encryption.
FAQs
Is ROT13 encryption?
No. The 'key' is fixed and well-known. It's a reversible substitution, useful only for hiding text at a glance.
Why 13?
13 is half of 26 - applying ROT13 twice returns the original. Letters non-alphabetic are left alone.
Does it preserve case?
Yes - 'Hello' becomes 'Uryyb', 'HELLO' becomes 'URYYB'.