What do the dots mean in Mastercode?

A solid dot means one digit of your guess is correct and sits in the right position. A hollow dot means a digit is in the secret code but in a different position.

How many guesses do I get in Mastercode?

It depends on difficulty: 12 guesses on easy, 10 on medium and 7 on hard. The number is shown under the difficulty selector.

Can the secret code repeat a digit?

No. The secret code is made of four different digits from 0 to 9, which narrows the possibilities and is worth using when you reason about your clues.

Mastermind Online Free – Crack the 4-Digit Code

Objective

Deduce a hidden 4-digit code using exact and partial match feedback. Think Mastermind: each guess narrows down the hidden code, so use the feedback strategically rather than guessing blindly.

How to play

Enter a 4-digit guess with no repeated digits.
Submit the guess to see exact matches (●) and partial matches (○).
Use the feedback to refine your next guess.
Crack the code before you run out of guesses.

Mastercode Top 5

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Playing as

Mastercode

Crack the 4-digit code (no repeated digits). ● = right digit, right spot. ○ = right digit, wrong spot.

Difficulty

Ready

0 moves

About Mastercode

Mastercode is a code-breaking game in the spirit of the classic Mastermind. The computer picks a secret four-digit number in which no digit repeats, and you try to uncover it with a limited number of guesses. After each guess you get a solid dot for every digit that is right and in the right place, and a hollow dot for every digit that is right but misplaced. Careful note-taking turns it into a deduction puzzle.

Tips and strategy

Open with a guess made of four different digits so the first feedback tells you about as many digits as possible at once.
Treat every row in the history as a clue. Ask which digits could produce exactly that number of solid and hollow dots, and cross off combinations that cannot.
Remember the secret never repeats a digit, so once you have located a digit you can rule it out of every other position.
A feedback row with no dots at all is gold: all four of those digits are absent, and you can use them as harmless fillers in later test guesses.
Choose a difficulty that matches your patience. Easy allows 12 guesses, medium 10 and hard only 7, so on hard each guess must be chosen with real care.

What it exercises

Mastercode builds deductive reasoning, working memory for earlier clues, and systematic elimination. You hold several possibilities in mind at the same time, test them against feedback, and adjust, which is the core loop of logical problem solving. It is also a good way to practise patience and staying organised across many guesses.

Frequently asked questions

What do the dots mean in Mastercode?: A solid dot means one digit of your guess is correct and sits in the right position. A hollow dot means a digit is in the secret code but in a different position.
How many guesses do I get in Mastercode?: It depends on difficulty: 12 guesses on easy, 10 on medium and 7 on hard. The number is shown under the difficulty selector.
Can the secret code repeat a digit?: No. The secret code is made of four different digits from 0 to 9, which narrows the possibilities and is worth using when you reason about your clues.

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