A free practice lab for the cipher types Science Olympiad Codebusters events commonly use. Pick a cipher and a difficulty, decode the challenge, then check your answer or reveal the solution. It runs in your browser, there is no account needed to try it, and it is unlimited on every OlyPrep plan, including Free.

Free on every planNo sign-in to tryTwelve cipher types

§ ABOUT THE LAB

Questions parents ask.

Q·01What is the Cipher Lab?
A practice tool for decoding ciphers, built for Science Olympiad Codebusters. Pick a cipher type and a difficulty and the lab generates a fresh challenge. Decode it, check your answer, or reveal the solution and study it. It keeps a list of your recent attempts. Everything runs in your browser with no AI involved, so a new challenge is ready the moment you ask for one.
Q·02Which ciphers does it cover?
Twelve cipher types in the open lab: Caesar, Atbash, Baconian, Morse, Affine, Vigenère, Railfence, K1 Aristocrat, Porta, Tap Code, PigPen and Knights Templar. Cryptarithm puzzles are there too for tournaments whose rules include them. A signed-in student sees the set their own tournament’s rules name.
Q·03Is the Cipher Lab free?
Yes, on every OlyPrep plan, including the Free plan, with no monthly cap. The Free plan meters AI chats, practice tests and study notes; the lab is not metered.
Q·04Do I need an account to use it?
No. Open this page and start; your recent attempts are kept in this browser. With a free OlyPrep account, a student’s finished challenges are also recorded to their account, so My report card can show their Codebusters progress cipher by cipher.
Q·05How does it relate to the Codebusters event?
Codebusters is the Science Olympiad event where students decode encrypted messages against the clock, and the lab is practice for exactly that. Answers are checked the way Codebusters papers usually are: a decoded quote with up to two wrong letters still counts as solved. Inside OlyPrep’s Codebusters prep spaces, each cipher’s study step opens this lab on that cipher, and for Bay Area ESO, Test day composes a full Codebusters paper with the same engine and scores it in points.