Bacon Cipher

The Bacon Cipher tool encodes any message into Francis Bacon’s 17th-century steganographic cipher and decodes it back again.

Each letter becomes a group of five symbols drawn from just two states — here written as A and B — so the word HELLO turns into five five-letter groups.

Switch to decode mode, paste the A/B groups, and the original text is reconstructed letter by letter.

Bacon’s cipher is historically important because the two states need not be A and B at all: they can be two fonts, two type weights, or upright versus italic letters hidden inside an innocent-looking passage, which is what makes it a true steganographic system rather than a simple substitution.

This tool uses the original 24-letter alphabet in which I and J share a code and U and V share a code, so a decoded message normalises J to I and V to U — expected behaviour for the classic variant.

Non-letter characters are ignored on encoding, and on decoding any symbols other than A and B are stripped before the groups are read, so spacing and punctuation will not break it.

Everything runs locally in your browser, so your message is never uploaded, and the tool works offline once loaded.