Guides5 min read
Bacon Cipher Guide: Encode, Decode, History
Bacon cipher explained: the full A/B encoding table, a worked encode/decode example, and how Francis Bacon hid messages inside ordinary text using typeface.
Bacon cipher
Encode or decode Bacon's cipher as groups of A and B. Free, private — nothing leaves your device.
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A/B groups0 characters
Your Bacon cipher result will appear here.Everything you need to read Bacon's cipher
24 and 26 letter versions
Switch alphabets to match the puzzle. Decoders disagree on which one they use, so you can try both.
Live results
The result updates as you type. No button to press.
A/B or 0/1
Decode groups written as A and B or as zeros and ones. Case and spacing don't matter.
100% private
Runs entirely in your browser. Nothing you type is uploaded or stored.
Encode or decode in three steps
- 1
Pick encode or decode, and a version
Use 26 letters for modern puzzles where every letter has its own code. Use 24 letters for the classic version where I/J and U/V share codes.
- 2
Type or paste your text
Each letter becomes five A or B symbols. When decoding, paste groups of A and B (or 0 and 1) and the tool reads them five at a time.
- 3
Copy or download the result
The result updates live. Copy it, download it as a .txt file, or use swap to run it back the other way.
Built for learning, puzzles, and quick checks
Bacon's cipher hides letters in two-symbol patterns. It's a favorite for puzzles and for explaining binary encoding, not for real secrecy.
Learning binary encoding
Bacon's cipher is a five-bit binary code from 1605, a neat way to see how letters become bits.
Puzzle hunts and escape rooms
Clues that hide a message in two fonts, two colors or A/B patterns are Bacon's cipher.
Decoding a steganography clue
Once you've sorted the two kinds of symbol into A and B, paste them in to read the message.
History of cryptography
Try the cipher Francis Bacon described, and see why he called it a way to hide a message in plain sight.
Frequently asked questions
What is the Bacon cipher?
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Bacon's cipher, also called the Baconian cipher, replaces each letter with a group of five symbols, each either A or B. A is AAAAA, B is AAAAB, and so on in binary order. Francis Bacon described it in 1605.
How do I decode a Baconian cipher?
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Switch to Decode, then paste the A/B groups. The tool reads them five at a time and turns each group into a letter. If your clue uses two fonts or two colors, write one kind as A and the other as B first.
What's the difference between the 24 and 26 letter versions?
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The original used 24 letters, with I and J sharing a code and U and V sharing a code. The 26-letter version gives every letter its own code. If your decoded text looks wrong, try the other version.
Can I use 0 and 1 instead of A and B?
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Yes. The decoder accepts either, in any case. It treats A or 0 as zero and B or 1 as one.
What does the / mean?
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It marks a space between words. The cipher has no code for spaces, and other punctuation and digits can't be carried so they're left out.
Is the Bacon cipher secure?
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No. It's a fixed substitution, so the same letter always gives the same code. Its real use was hiding the pattern inside innocent-looking text. It's for puzzles and learning only.
Is my text uploaded anywhere?
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No. Everything runs in your browser, and nothing you type is sent to a server.
Try the Bacon cipher now
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