ROT13 / Caesar Cipher
Apply ROT13 (a shift of 13) or a custom Caesar shift to text. This is not encryption and provides no security. Nothing is uploaded.
ROT13 and Caesar Cipher
ROT13 replaces each letter with the one 13 places along the alphabet. Because the alphabet has 26 letters, applying it twice returns the original text. A Caesar cipher is the same idea with any shift. Neither one has a key, so neither is encryption — they hide text from a casual glance and nothing more.
How it behaves
- Letters are shifted; case is preserved.
- Digits, punctuation and other characters are left unchanged.
- ROT13 is its own inverse; a custom shift can be reversed with 26 minus the shift.
Frequently asked questions
Is ROT13 encryption?
No. ROT13 is a simple letter substitution with no key; it offers no security. It is a puzzle and obfuscation device, not encryption.
Does it apply to ROT13 and back the same way?
Yes. ROT13 is its own inverse, so applying it twice returns the original text.
What happens to digits and punctuation?
They are left unchanged; only letters are shifted.
Can I choose a different shift?
Yes. The Caesar mode lets you pick a shift from 1 to 25.
Is case preserved?
Yes. Upper-case and lower-case letters keep their case.
Is my text sent to a server?
No. The conversion is done locally in your browser.
Related: the text case converter and word counter, or browse every browser-only tool on the all tools page.