Cipher Encoder

• Caesar shifts every letter along the alphabet by the number of positions you choose. The famous ROT13 is the same cipher with a shift of 13;
• Vigenère gives each letter its own shift, set by the current letter of the key. The key repeats for the whole length of the text;
• Atbash reverses the alphabet: the first letter swaps with the last. The cipher is its own inverse, so decryption is the same operation as encryption.

Picking the shift

If the ciphertext belongs to someone else and the shift is unknown, press "Pick the shift" in decryption mode. The tool tries every option and moves the ones that look like readable text to the top: candidates are ranked by how closely their letter frequencies match the language. Clicking a result applies its shift.

This is not security

All three ciphers break on paper. Caesar falls after thirty tries at most, Atbash has no key at all, and the method for breaking Vigenère has been known since the 19th century. They work for puzzles, school exercises, and hiding an answer from a casual glance.

For real protection people use algorithms like AES with keys too long to brute-force.