Atbash cipher

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All tools β€Ί Replacing letters

Atbash cipher

Mirror the alphabet: the first letter becomes the last, and doing it again gives the text back.

It runs entirely in this browser tab: the text you paste is never uploaded, and the tool makes no network request while it works. Open your browser's network panel and try it β€” nothing leaves the page. There is no sign-up and no limit beyond what your own browser can hold.

Settings

Alphabet
Choices: Latin A–Z, Slovak, with accents, Greek α–ω, Own.
Your own alphabet
The letters in order, each one once
Keep spaces and punctuation
Off, the result is letters only β€” which is how a cipher was actually sent.
Show the working
Replaces the result with the cipher's own workings: the grid or key it is using, or what it did to each letter.

How to use it

  1. Paste your text into the box above, or open a file.
  2. Adjust the settings beside it until the result is what you wanted.
  3. Copy the result, or save it as a file. The result updates as you type.

Questions

Is my text uploaded anywhere?
No. This page carries the whole tool as WebAssembly and runs it on your own device. Nothing you paste is sent anywhere.
Is this secure?
No. Every cipher on this site is a puzzle cipher, and the tool says so on each result. They are for escape rooms, cryptograms, coursework and historical curiosity.
Can I get this result again later?
The settings travel in the page's address, after the #, so a link reproduces them exactly β€” key included β€” and the fragment of an address is never sent to a server. Your last settings are also remembered on this device, which is worth knowing before you type a key you care about.
Is there a version that is not a web page?
Yes. The same ciphers are built as a desktop application from the same code, with a save dialog instead of a download and no network code at all.

Other tools for replacing letters

Substitution cipher
Give the alphabet any order you like, or let letter frequencies suggest one to start from.

A1Z26
Letters as their position in the alphabet, and numbers read back even when nothing separated them.

Bacon cipher
Five of two symbols per letter β€” and a message that can hide in the capitals of an innocent text.

All twenty ciphers