Connect logic gates to match the required output signals
Circuit Builder is a free browser-based logic gate puzzle game where you design digital circuits to produce specific output signals. Starting with the simplest single-gate puzzles and progressing through 25 increasingly complex challenges, you'll learn how computers process information at the most fundamental level — through binary signals and boolean logic.
Each puzzle gives you a set of input signals (0 or 1) and asks you to arrange logic gates so the circuit produces a required output. Drag gates onto the board, connect them with wires, and click Simulate to watch electrical signals flow through your creation.
Drag logic gates from the component tray onto the circuit board. Click a gate's output pin to start drawing a wire, then click an input pin to complete the connection. Toggle input values by clicking the input nodes on the left. When you think your circuit is ready, click Simulate to run the signals and see if your output matches the required values shown on the right.
Your score is based on efficiency — solving the puzzle with fewer gates earns more stars. Every level has a minimum gate solution; finding it earns a perfect 3-star rating. Use keyboard shortcuts (A, O, N, X, D) to quickly add gates, and Delete to remove the selected gate.
No! The game teaches you as you go. Start with simple NOT gates and gradually learn AND, OR, XOR, and NAND gates through intuitive puzzles.
Five gate types: AND (both inputs must be 1), OR (either input is 1), NOT (inverts input), XOR (inputs must differ), and NAND (NOT-AND).
Each level awards up to 3 stars based on the number of gates used. Fewer gates = more stars. Try to find the most efficient solution!
Last updated: April 2026 · ← whatifs.fun