liminfoLogic Gate Simulator
Free web tool: Logic Gate Simulator
Logic Gate Simulator
Select a logic gate, set inputs, and see the output with truth table.
Output is 1 only when both inputs are 1
Truth Table
| A | B | Output |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
About Logic Gate Simulator
The Logic Gate Simulator is an interactive browser-based tool for visualizing the behavior of fundamental digital logic gates including AND, OR, NOT, NAND, NOR, XOR, and XNOR. Each gate is rendered with an SVG diagram showing input lines and an output line, with a bubble indicator on inverted gate types (NOT, NAND, NOR, XNOR). You can toggle each input between 0 and 1 with a single click and instantly see the computed output, making it ideal for understanding boolean logic concepts hands-on.
This tool is widely used by electrical engineering and computer science students who are learning combinational logic design, as well as educators who need a quick demonstration aid in the classroom. Digital circuit designers and hobbyists building with microcontrollers or FPGAs also use it to verify gate behavior before implementing in hardware or HDL code. The simulator covers all seven basic gate types, each with a dynamically generated truth table so you can cross-reference any input combination at a glance.
Technically, all gate logic is computed in the browser using JavaScript bitwise and equality operators — AND uses &, OR uses |, XOR uses ^, NOT inverts the single input, and NAND/NOR/XNOR are derived from their base gates. The truth table is generated with useMemo so it only recalculates when the gate type changes, keeping the UI responsive. The currently active input row is highlighted in the truth table, providing immediate visual feedback that connects the toggle inputs to the corresponding table row.
Key Features
- Supports all 7 fundamental gate types: AND, OR, NOT, NAND, NOR, XOR, XNOR
- Interactive SVG gate diagram with input and output lines rendered in real time
- Bubble (inversion circle) correctly shown on NOT, NAND, NOR, and XNOR gate outputs
- Click-to-toggle input buttons (A and B) with green highlight when high (1)
- Dynamically generated truth table with the active row highlighted in blue
- Plain-language gate description shown below the selector for quick learning
- 100% client-side — no data is sent to any server, works offline
- Dark mode support and fully responsive layout for all screen sizes
Frequently Asked Questions
What logic gates does this simulator support?
The simulator supports all seven basic gate types: AND, OR, NOT, NAND, NOR, XOR, and XNOR. You can switch between them instantly using the gate selector buttons at the top of the tool.
How do I toggle the input values?
Click the square button labeled A or B to toggle that input between 0 (LOW) and 1 (HIGH). The button turns green when the input is 1. For the NOT gate, only input A is used because it is a single-input gate.
What is the difference between NAND and AND?
NAND is the complement of AND. While AND outputs 1 only when both inputs are 1, NAND outputs 0 only when both inputs are 1 (and 1 in all other cases). NAND is called a universal gate because any other gate can be built using only NAND gates.
What is the difference between XOR and XNOR?
XOR (exclusive OR) outputs 1 when the two inputs are different (one is 0 and the other is 1). XNOR is its complement — it outputs 1 when both inputs are the same (both 0 or both 1). XNOR is sometimes called an equality gate.
Why does the truth table highlight one row?
The highlighted row in the truth table corresponds to the current combination of input A and input B you have set using the toggle buttons. This makes it easy to see where your current inputs land in the full truth table.
Can I use this to learn for a digital electronics exam?
Yes, this is an excellent study tool. You can work through every combination for each gate type and verify your understanding of boolean logic. The plain-language description of each gate helps reinforce the concept alongside the visual and tabular representations.
Does this simulator show logic gate symbols correctly?
The simulator uses a simplified rectangular SVG representation with the gate name inside, which is a clean and readable format. The inversion bubble is drawn on the output line for NOT, NAND, NOR, and XNOR gates, correctly following standard digital logic notation.
Is this tool free and available without sign-up?
Yes, the Logic Gate Simulator is completely free to use with no account required. All computation happens in your browser, so it also works offline after the page has loaded. There are no usage limits or ads that block functionality.