All tools › Grids and coordinates
Playfair cipher
Encipher letters in pairs by the rectangle they make in the square, and see which rule moved each one.
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 — nothing leaves the page. There is no sign-up and no limit beyond what your own browser can hold.
Settings
- What to do
- Choices: Encipher, Decipher.
- Keyword
- Text you supply.
- Two letters in one cell
- Twenty-six letters do not fit in twenty-five cells. Whoever wrote the message already chose which one goes. Choices: I = J, Q left out.
- Filler letter
- Goes between a doubled pair and onto the end of an odd message, because Playfair works in pairs.
- 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
- Paste your text into the box above, or open a file.
- Adjust the settings beside it until the result is what you wanted.
- 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 — key included — 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 grids and coordinates
Polybius square
Every letter as a pair of coordinates in a five-by-five square you can key yourself.
Tap code
Letters as two runs of taps on a wall, written in dots or numbers and read back either way.
Rail fence cipher
Write the message in a zigzag and read it off by rows — or try every height at once to read it back.
All twenty ciphers