Atbash Cipher

Reverse the alphabet — A↔Z, B↔Y, C↔X. The same key encrypts and decrypts.

Input (type to encode — or decode)

Output

Svool Dliow

Substitution Table

Plain	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V	W	X	Y	Z
Cipher	Z	Y	X	W	V	U	T	S	R	Q	P	O	N	M	L	K	J	I	H	G	F	E	D	C	B	A

How the Atbash Cipher Works

The Atbash cipher is one of the oldest known ciphers — each letter is replaced by the letter at the opposite end of the alphabet: A→Z, B→Y, and so on. Because it is its own inverse, the same operation both encrypts and decrypts. Non-alphabetic characters (spaces, numbers, punctuation) are left unchanged.

Built and maintained by Meet Shah · Last updated 19 July 2026

What this tool is used for

Solving a puzzle whose ciphertext is a mirrored alphabet, recognisable once you check A against Z.
Demonstrating a fixed substitution with no key at all, as a contrast to a Caesar shift.
Decoding a historical or literary reference that uses the classical Hebrew mapping.
Producing lightly obscured text where the mechanism is meant to be discoverable.
Checking whether an unreadable string is simply the alphabet reversed.

Frequently Asked Questions

Why is there no encode and decode button?: Because the mapping is its own inverse: A becomes Z and Z becomes A, so running it twice returns the original. That is true of any mirror substitution, and it is why Atbash needs no direction setting — the same operation covers both.
Where does the name come from?: From the Hebrew letters it pairs: aleph with tav, beth with shin — A-T-B-SH. It is one of the oldest recorded ciphers, and it appears inside the Hebrew Bible, where Sheshach in Jeremiah is Atbash for Babel, apparently to avoid naming Babylon directly.
What happens to numbers and punctuation?: They pass through untouched — only A–Z and a–z are mirrored, and letter case is preserved. That keeps the shape of the text intact, so word lengths, spacing and any digits stay readable, which is exactly why Atbash is weak.
How is it different from a Caesar shift?: A Caesar cipher slides the alphabet by some amount and needs the same amount to undo; Atbash reflects it, which is a fixed operation with no key at all. Atbash is in fact the special case of an affine cipher with a = −1 and b = 25.
Can it be broken without any effort?: Instantly, by anyone who recognises it — there is no key to guess. Even without recognising it, letter frequencies give it away immediately: the commonest English letter E maps to V, so a ciphertext full of Vs is a strong hint. Use it for puzzles, never for secrets.

Common errors and gotchas

Looking for separate encode and decode actions. The mapping is symmetric, so one operation does both directions.
Expecting a key. There is none, which is precisely why it offers no security whatsoever.
Assuming digits and punctuation are transformed. Only the twenty-six letters are mapped.
Confusing it with a Caesar shift, which rotates the alphabet rather than reflecting it.
Treating a successful decode as a cryptographic result. It is a lookup table anyone reconstructs in seconds.