Tools · Classical ciphers
Pigpen cipher
The Freemasons’ pigpen cipher: letters in grids and crosses. Type text or decode by clicking symbols.
Runs in your browser. Your text goes nowhere.
How to use it
In “Text → symbols” mode, type your message and it turns into pigpen symbols at once. “Download SVG” saves the message as a picture you can print or put on a card. In “Symbols → text” mode, click the symbols on the keyboard in the order they appear in the message: every symbol is labelled with its letter, and the decoded text builds up in the field below.
The classic pigpen covers the 26 Latin letters. Digits and punctuation are left as they are; other letters are skipped.
How it works
You draw four figures: two noughts-and-crosses grids and two diagonal crosses. Letters A–I go into the first grid, J–R into the second, S–V into the first cross and W–Z into the second. Every cell of the second grid and the second cross gets a dot. A letter is written as the shape of its cell: A is the corner “⌟”, E a closed box, S the wedge “V”. If the cell has a dot, the dot goes inside the symbol. The key is shown below the tool.
Underneath it all, pigpen is an ordinary simple substitution: one symbol, one letter. So frequency analysis breaks it just the same. The commonest symbol in an English message is almost certainly E, the box.
A little history
Grid ciphers of this kind go back at least to the eighteenth century. Freemasons' lodges used them, which is why it is also called the Freemasons' cipher, and the name pigpen comes from the little pens the shapes resemble. It turns up on gravestones, in soldiers' notes and in novels. Today it is a favourite of treasure hunts and escape rooms: it looks mysterious and falls in a minute.
FAQ
The letters in my message are arranged differently. Why?
There are several layouts: some fill the grid by columns, others put a cross between the grids. If the result makes no sense, crack the message as a plain substitution, by frequencies, in the substitution tool.
Can I write numbers in pigpen?
The classic version has no digits. Spell numbers out in words.
Is it safe to type my text here?
Yes. Everything runs in your browser and nothing is sent to a server.