Someone sent you a secret message.
Caesar cipher
Daily Cipher
A new coded quote every day, the same for everyone. Each code symbol always stands for the same real letter, so when you fill in one box, every matching box fills in too. The puzzles get harder through the week, from a gentle Monday to a fiendish Sunday.
Crack a Message
Paste any encoded text. The letter counts show its fingerprint, and the identifier suggests which cipher made it, with a key when it can find one.
Letter frequency
Cipher identifier
Learn a Code
Step-by-step lessons with practice games. Each one saves your stars, so you can stop any time and pick up where you left off.
Pick what to learnLearn Morse Code
Learn Morse the way radio operators do: by sound. Each lesson adds one new character, played at real speed with extra space between letters so you have time to think. Score 90% on a round and the next character unlocks. Your progress is saved in this browser.
Lesson 1
Press Start a round, then type each character you hear.
On a keyboard, type what you hear and press the space bar to replay.
Hold the button or the space bar. A short press is a dot, a long press is a dash. Pause to finish a letter.
Dot and dash chart
Handy for looking something up, but try not to learn from it. People who learn Morse by sound get much faster than people who picture dots and dashes.
Learn Pig Latin
Pig Latin is a secret way of talking that kids have shared on playgrounds for well over a hundred years. Learn it one rule at a time: each lesson shows a rule in action, then gives you words to try. Pass a lesson to unlock the next one. Your stars are saved in this browser.
Practice uses words from the lessons you have unlocked.
Learn Binary
Every computer, phone and game console stores everything (words, pictures, music) as long strings of 1s and 0s called binary. Learn to read and write it with light bulbs and magic dot cards. Pass a lesson to unlock the next one. Your stars are saved in this browser.
Type in either box and the other one updates.
Learn Hex
Hexadecimal, or hex for short, is a way of counting with sixteen digits: 0 to 9, then A to F. Programmers use it as a shortcut for binary, and every color on a web page has a hex code. Pass a lesson to unlock the next one. Your stars are saved in this browser.
Type in any box and the others update.
Kids' Puzzle Maker
Make a fresh code-breaking puzzle for kids aged 6 to 12. Solve it right here on screen, or save it as a worksheet to print. Every press of New puzzle gives a different one.
Step 1: Pick a puzzleGreat for party invitations, treasure hunts, or a note in a lunchbox.
Code Hangman
The hidden word is written in a secret code, and every code follows a rule. Use the clue to crack the rule, then read the word and solve it, or guess letters to uncover more of the code. Nobody gets hanged here: wrong guesses just set off the vault alarm.
The letters stay hidden as you type, so Player 2 can't peek. Letters and spaces only.
Codebreaker's notebook
Every letter you uncover shows its code here. Dashed boxes come from your clue, and faded ones aren't in the word. Look for the pattern!
Logic Games
Classic brain-teasers that take planning, patience and clever thinking. Every one has a "Show me how" button if you get stuck.
Pick a gameUnscramble Words
Type a jumble of letters to find every English word hiding inside it. Use a question mark for a blank that can stand for any letter. To solve a scrambled sentence, put a space between each jumbled word.
Write a Secret Letter
Hide a message inside an ordinary-looking letter. Pick how the letter will travel, write it, and the page tucks your secret inside. Whoever receives it can uncover the message here with Read a secret letter.
Uses the Vigenère cipher. Your reader will need the keyword too, so share it separately.
Only needed if the sender gave you one.
Step 3: See what's hiddenHolding a printed letter with italic code?
Go through the letter and type A for each regular letter and B for each slanted one. Skip spaces and punctuation. You can stop when you reach five B's in a row.
Hide a Message in a Picture
Steganography hides the fact that a message exists at all. This tool tucks your text into the tiniest color details of a picture, changes too small for anyone to see. Send the picture to a friend, and they can use this same page to read it.
Put a secret message inside a picture, then save the picture to share.
Any photo from your device works. No picture handy? Use the sample to try it out.
Without a keyword, anyone who uses this page on your picture can read the message. With one, the message is also scrambled with the Vigenère cipher, so they need the keyword too. Share it with your friend separately, not in the same message as the picture.
Step 4: Hide itOnly needed if the sender told you one. If the message below looks like gibberish, you probably need it.
Your picture will appear here.
Hidden layer shows the last bit of every color as pure black or white. A hidden message shows up as a band of static along the top.
Send the saved PNG as a file, for example as an email attachment or through a file-sharing link. Chat and social apps usually shrink or convert pictures, and that erases the message. Screenshots erase it too.