Caesar Cipher
Khoor, Udqjgrp!
Shifted locally in your browser. Letters A–Z and a–z move by the chosen amount while case is preserved; digits, punctuation, and spaces pass through unchanged.
ROT13 uses a shift of 13 and is its own inverse, so encode and decode produce the same result.Encode text with a Caesar shift
Pick a shift from 0 to 25 (or the ROT13 preset) to move each letter forward through the alphabet. The same shift reverses the message in decode mode.
When to use this tool
Reach for the Caesar cipher to solve puzzle and CTF challenges, teach how substitution ciphers work, or lightly obscure spoilers and answers. ROT13 is the classic one-click preset; any shift from 0 to 25 encodes and decodes on a single page.
Privacy and limitations
Everything runs locally in your browser; nothing is sent anywhere. This is a simple letter-shift cipher, not real encryption — it only shifts A–Z and a–z, leaves digits and symbols untouched, and offers no Vigenère, keyword, or auto-solving features.