Code Buddy: Secret Messages
Only your friend can read it
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
Pick a word. Tell one friend and nobody else. Everything you type turns into little symbols, and the only person who can turn them back is the one who knows the word.
Pick a word. Any word — your dog's name, your favourite band, something daft. Tell one friend and nobody else.
Now type a message. Watch it turn into little symbols: stars, squares, moons, circles. To anyone who doesn't know your word it's gibberish. To your friend it's a message.
HOW IT GOES
1. You both type in the same word.
2. You write something. It turns into symbols as you go.
3. Send the symbols however you like — a chat, a note pushed under a door, chalk on a wall.
4. Your friend types them in and reads what you said.
FLASH IT ACROSS A DARK ROOM
This is the good bit. Instead of sending symbols, your phone can blink the message out loud: the screen, the torch, beeps, buzzes, or all four at once.
Your friend watches from the other side of the room — or the garden, or the next tent — and taps along on their phone as it arrives. No wifi. No signal. No internet at all. Just light going across a dark room and somebody reading it.
BECOME A CODEBREAKER
Open the Grid tab and see exactly what your word did: it shuffles the alphabet into a six by six square — every letter, and the numbers too — and each one becomes a row and a column. Two symbols each.
Once you've seen it, you can do the whole thing on paper without the app. This trick is over two thousand years old and named after the Greek historian who wrote it down. It still works.
MAKE IT YOUR OWN
Bored of stars and squares? Build a symbol pack out of whatever you like and send it to your friend as a link, so only the two of you are using it.
And when it all starts feeling too easy, switch on hard mode, where every letter shifts along as the message goes, so the same letter never looks the same twice. Good luck.
THINGS TO TRY
• Leave a coded note on the fridge
• Hide clues for a treasure hunt round the garden
• Flash a message between two bedroom windows
• Pass a note across a room where you're supposed to be quiet
• Race a friend to crack a message using nothing but pencil and paper
• Invent a symbol pack nobody else in the world has
FAIR WARNING
This is a puzzle, not a lock. It's the sort of code a patient person cracks with a pencil and an afternoon — which is exactly what makes it fun to break as well as fun to write. So keep it to jokes, plans and nonsense. Don't put anything in it you'd mind somebody working out.
Nothing you write leaves your phone. No account, no sign-up, no server, nobody watching. It all happens on the device in your hand.
ABOUT THE FLASHING
Sending a message flashes the screen, and the torch if you switch it on. It never goes faster than two and a half flashes a second. If you'd rather not use light at all, the sounds and buzzes work perfectly well on their own.
WHAT IT COSTS
Nothing, to write, read, flash and follow along, with the Geometry symbol pack. One optional purchase adds the other packs, packs you build yourself, sharing them with friends, and hard mode.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
The developer, Zander Martineau, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Zander Martineau
- Size
- 4 MB
- Category
- Utilities
- Compatibility
Requires iOS 18.0 or later.
- iPhone
Requires iOS 18.0 or later. - iPad
Requires iPadOS 18.0 or later. - Mac
Requires macOS 15.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 2.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Unlock everything $2.99
- Copyright
- © 2026 Zander Martineau