🔃 Atbash Cipher
Flip the alphabet: A becomes Z, B becomes Y. The ancient Atbash cipher — the same operation encodes and decodes.
Transformed in your browser — nothing you type is uploaded.
How the atbash cipher works
Atbash reverses the alphabet: each letter is replaced by the one the same distance from the other end, so A↔Z, B↔Y, C↔X, and so on. Because the mapping is symmetric, applying it a second time restores the original — one operation both encodes and decodes. Originally a Hebrew cipher, it's among the oldest known substitution ciphers.
Atbash appears in the Hebrew Bible and, more recently, as a puzzle in popular fiction. Like all simple substitutions it offers no security — a single fixed mapping is trivially reversed — but it's a neat, self-inverse curiosity and a common layer in cipher puzzles.
Frequently asked questions
What is the Atbash cipher?
A substitution cipher that maps each letter to its mirror in the alphabet: A↔Z, B↔Y, C↔X, through M↔N. It originated as a Hebrew cipher and is one of the oldest known.
Why is there only one button?
Because Atbash is its own inverse — reversing the alphabet twice returns you to the start. The same operation encodes and decodes.
Is Atbash secure?
No — it's a single fixed substitution with no key, reversible instantly. It's of historical and puzzle interest, not for protecting real data.
What does "HELLO" become in Atbash?
SVOOL. H↔S, E↔V, L↔O, L↔O, O↔L.
Does this run locally?
Yes — the mapping is applied in your browser; nothing is uploaded.