Caesar Cipher Encoder and Decoder

A Caesar cipher with a shift of 13. Because the alphabet has 26 letters, applying it twice returns the original - which is why it is used to hide spoilers rather than secrets.

Try all 25 shifts and read which one produces words. That is why this tool lists them all - with only 25 possibilities there is nothing to break.

Not remotely. It has 25 possible keys and falls instantly to frequency analysis. It is a teaching tool and a party trick, never a security measure.

They pass through unchanged. Only the 26 letters are shifted, and case is preserved.

Try all 25 shifts and read which produces words - a brute force that takes seconds. For longer texts, letter frequency alone reveals the shift immediately.

ROT13 is a Caesar cipher with the shift fixed at 13. Because 13 is half of 26, encoding and decoding are the same operation.

The key space is 25. Any computer tries every option instantly, and even by hand frequency analysis breaks it in minutes. It was adequate when most opponents could not read at all.

A Caesar cipher with a shift that changes per letter according to a keyword. It resisted analysis for three centuries and is still trivially broken today, but it is the natural next step up.