Caesar brute force
Caesar brute force, classical cipher, a puzzle not a protection, computed on your device.
Runs on your device. The file is never uploaded.
Caesar brute force prints all 25 shifts of your text at once, one line each, headed by the shift number padded to two columns. Spotting the readable line is left to your eye. No scoring, dictionary or frequency check runs here, and every line holds a full copy of the input.
Questions
What does it output?
Twenty-five lines, one per shift from 1 to 25, each labelled with the shift number and followed by the whole text decoded that way. You read down the list and pick the line that turns into readable text. The page presents these as candidates rather than as a single answer, because the tool makes no choice for you.
Does it tell me which shift is correct?
No. There is no scoring, no dictionary and no language detection here; it simply prints every possibility. That differs from XOR brute force on this site, which does score its candidates and shows only the top five. For Caesar the list is short enough to scan by eye in a second.
Why does it work at all?
Because a Caesar cipher has only 25 possible keys. Trying all of them takes no time, which is exactly why the cipher provides no security. Anything encoded with Caesar encode is readable by anyone with this page open, or with a pencil and a few minutes.
Will it break a Vigenere or a substitution cipher?
No. It only tries the 25 single-alphabet shifts. A Vigenere cipher with a multi-letter key and a general substitution cipher with an arbitrary 26-letter key are both outside what it attempts. There is no automatic solver for either on this site: Vigenere decode and Substitution cipher decode both need the key from you.
What happens to non-letters?
Every line keeps them exactly as they appear in your input. Only A to Z and a to z are shifted, case included. Because each of the 25 lines is a full copy of your text, the output is roughly twenty-five times the size of the input, so trim long files to a sample first.
Does anything get sent anywhere?
No. All 25 shifts are computed in a Web Worker in this tab and shown on the page. Nothing is uploaded, nothing is stored between runs, and it works offline after the first visit. That means you can throw a ciphertext from a puzzle or a capture-the-flag challenge at it without the text going anywhere.