What you can do here
You can use every tool without an account, and the tools run in your browser:
- Caesar cipher tool and solver
- Caesar cipher wheel
- Vigenère cipher
- ROT13, Atbash and substitution ciphers
- Frequency analysis
Next to the tools there are guides and articles on how these ciphers work and how to break them, lesson ideas for teachers, and for developers a public API, a JavaScript library and programming tutorials.
Who the site is for
Mainly school and university students learning cryptography or computer science. It is also useful for teachers, developers, puzzle solvers and anyone curious about secret messages.
Six languages
The site is available in English, German, Spanish, French, Indonesian and Polish. The Caesar tool also supports Polish, German, Spanish and French letters and lets you set your own alphabet.
How we check our content
We compute worked examples with the same code the tools use, and our newer articles list their sources. We are still rewriting some older pages. If you find a mistake, please tell us.
What these ciphers cannot do
Classical ciphers are for learning and puzzles. They do not protect real data, so never use them for passwords or private information. From the Caesar cipher to modern encryption explains why.
How the site is funded
The site is free to use and is paid for by ads and by voluntary support through Buy Me a Coffee. The privacy policy explains what the ads and statistics involve.