What ciphers does this tool support?

The helper supports Caesar shifts, ROT13, the Atbash cipher and fully custom substitution alphabets. It can both encode and decode, and includes a brute-force view so you can see every Caesar shift at once when you do not know the key.

Who might find this cipher helper useful?

The tool is intended for puzzle designers, geocachers, escape room creators, ARG builders, teachers introducing classical cryptography and anyone who wants to lightly obfuscate text. It is not designed for serious security use.

Does this tool provide strong encryption?

No. Classical substitution ciphers such as Caesar, ROT13 and Atbash are easily broken and should not be used to protect sensitive data. They are best suited to games, riddles and teaching basic cryptography concepts.

Does the tool store or send my text anywhere?

No. All encoding and decoding happens locally in your browser in plain JavaScript. Nothing is uploaded or stored on a server, and refreshing the page clears everything.

Substitution Cipher & Obfuscated Text Helper

Encode and decode short messages using classic substitution ciphers — handy for puzzle trails, geocaches, escape-room clues, classroom exercises, or just lightly obscuring spoilers. Everything runs locally in your browser.

Who might find this useful? Puzzle designers, geocachers, ARG builders, teachers demonstrating basic cryptography, and anyone who occasionally wants a quick Caesar or ROT13 helper without installing anything.

Step 1

Paste text & choose a cipher

Input text

Letters A–Z/a–z are transformed; everything else (spaces, punctuation, digits) is preserved as-is.

Cipher settings

Cipher type

Caesar shift (−25 to +25)

Positive = shift forward (A→D with +3), negative = shift backward.

Step 2

Result & Caesar brute-force helper

Output text

Brute-force Caesar / ROT helper

If you have a Caesar-style ciphertext but don’t know the shift, use this to see all possible shifts at once. Pick the line that looks like sensible plaintext.

Substitution cipher helper FAQ

A few notes on how the ciphers are implemented here and what they’re good (and not good) for.

What’s the difference between Caesar and ROT13?

A Caesar cipher shifts letters by a fixed amount around the alphabet, e.g. with a shift of +3, A→D, B→E, C→F, and so on. ROT13 is just a special case where the shift is fixed at 13 on the 26-letter Latin alphabet — applying it twice returns you to the original text.

In this app, “Caesar” lets you choose any shift from −25 to +25, while “ROT13” is a shortcut for the common +13 rotation.
How do I use a custom substitution alphabet?
Leave the plain alphabet as ABCDEFGHIJKLMNOPQRSTUVWXYZ in most cases, then enter a 26-letter cipher alphabet that maps each plain letter to a new letter. For example:
- Plain: ABCDEFGHIJKLMNOPQRSTUVWXYZ
- Cipher: QWERTYUIOPASDFGHJKLZXCVBNM
When you choose “Encode”, A→Q, B→W, C→E, etc. When you choose “Decode”, the mapping is inverted so Q→A, W→B, E→C, and so on.
Does this preserve capitalisation and punctuation?
Yes. The app:
- Transforms A–Z and a–z, preserving upper/lower case.
- Leaves digits, spaces and punctuation unchanged.
This makes it easier to keep formatting and numbers intact while still obfuscating the letters.
Is this suitable for real security or private messages?
No. Classical substitution ciphers are extremely weak and can be broken quickly with frequency analysis and modern tools. They are best used for:
- Puzzles, treasure hunts and geocaches.
- Escape rooms and ARGs.
- Introductory classroom exercises about cryptography.
For anything genuinely sensitive, you should use well-established, modern cryptography rather than simple substitution ciphers.

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