Polybius Square client-side
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How to use Polybius Square

The Polybius square arranges the alphabet in a 5×5 grid and replaces each letter with its row number followed by its column number. Since the grid only has 25 cells, I and J usually share the same cell. You can scramble the grid with a keyword to strengthen the cipher. The tool encrypts, decrypts and displays the generated grid. Everything is processed in your browser.

Encode each letter as coordinates on a 5×5 grid.

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How to use Polybius Square

The Polybius square arranges the alphabet in a 5×5 grid and replaces each letter with its row number followed by its column number. Since the grid only has 25 cells, I and J usually share the same cell. You can scramble the grid with a keyword to strengthen the cipher. The tool encrypts, decrypts and displays the generated grid. Everything is processed in your browser.

Frequently asked questions

Why do I and J share a cell?

To fit the 26 letters into a 25-cell (5×5) grid. On decryption the “I/J” cell is read from context.

What is the keyword for?

It fills the grid starting with the keyword's letters, scrambling the alphabetical order and making analysis harder.