Caesar Cipher Encoder and Decoder
Shift letters to encode or decode a Caesar cipher with any shift value, and brute force all 25 shifts to crack a message you do not have the key for.
Encode, decode, and crack a Caesar shift
The Caesar cipher shifts every letter forward by a fixed amount, so with a shift of 3 the letter A becomes D. Pick a shift, and you get the encoded version and the decoded version side by side, since decoding is just shifting the other way. Only letters move; spaces, digits, and punctuation are left exactly as they are, and case is preserved. If you have a scrambled message but not the key, the brute force panel lists all 25 shifts at once so you can scan for the line that reads like real words.
Real secrets deserve real protection
A Caesar cipher is a fun puzzle, not security. For the things that actually matter, you want strong encryption and a place that remembers. Relic is an end-to-end encrypted memory for everything you copy, searchable on every device and kept for as long as you want, so only you can ever read it. The cipher tool is free, and your real data stays genuinely private.
Frequently asked questions
What is a Caesar cipher?
It is one of the oldest ciphers: you shift every letter forward by a fixed number of places in the alphabet. With a shift of 3, A becomes D and B becomes E. Named after Julius Caesar, who reportedly used a shift of 3 for his correspondence.
How do I decode a Caesar cipher without the key?
Use the brute force panel. Because there are only 25 possible shifts, the tool decodes the message with every shift at once and lists them. Read down the list and pick the line that reads like real words. That is exactly why the cipher is trivial to break.
How is ROT13 related to the Caesar cipher?
ROT13 is just a Caesar cipher with a shift of 13. Because the alphabet has 26 letters, applying a shift of 13 twice returns the original, so the same operation both encodes and decodes. Set the shift to 13 here and you have ROT13.
Does the Caesar cipher change numbers, spaces, and punctuation?
No. Only letters are shifted, and case is preserved, so a capital stays capital. Spaces, digits, and punctuation pass through untouched. That keeps the structure of a message readable, which unfortunately also makes it easier to crack.
Is a Caesar cipher secure?
Not at all. With only 25 shifts, anyone can brute force it in seconds (this page does it for you), so it is great for puzzles, teaching, and games, but useless for real secrets. For actual secrecy use real encryption, like our encrypt text tool or an end-to-end encrypted store.