How do I save and share a circuit?

Use File → Save (Ctrl+S) to download a .lgs file. Re-open it with Ctrl+L (Restore Workspace). To share a live session, use the Collaborate button to generate a URL — anyone who opens the link joins instantly without an account. Use File → Export Image to save a PNG snapshot for documentation.

Design circuits.
Simulate logic.

Gate Lab is a free, browser-based digital circuit simulator. Build and test anything from basic logic gates to custom CPUs — with real-time simulation and live collaboration.

LAUNCH GATE LAB View Examples

40+ Built-in component types

Programmable Components Custom scripting language

Free No account needed

Capabilities

Everything you need to design digital circuits

A comprehensive toolkit for students, engineers, and educators — all in your browser.

Logic Gates

AND, OR, NOT, NAND, NOR, XOR, XNOR — all with configurable input counts. Wire them together and simulate instantly.

Flip-Flops & Registers

D, T, SR, JK flip-flops with CLK and RST. 4, 8, and 16-bit registers with load, increment, and clear controls.

Memory & Counters

128×4 and 128×8 RAM with a built-in memory editor. 2, 4, and 8-bit synchronous counters with reset.

Displays

7-segment display and decoder, character LCD (1×16, 2×16, 4×16), and matrix display up to 64×64 pixels.

Oscilloscope

1, 2, 4, or 8-channel oscilloscope. Attach to any wire and view HIGH/LOW waveform history over time.

Truth Table Component

Define combinational logic by filling in a table — up to 8 inputs and 8 outputs. No scripting required.

Programmable Components

Write combinational or clocked logic in the built-in scripting language. Supports internal state, clock events, and custom pins.

Signal Tunnels & Buses

Route signals across the canvas without wires using tunnels. Multi-bit bus components handle parallel data paths.

Export & Share

Save workspaces as .lgs files. Export circuits as PNG or SVG. Import memory contents with .lgm files.

Workflow

Three steps to a working circuit

From a blank canvas to a running simulation in minutes — no setup required.

Place Components

Open the component panel and drag any gate, flip-flop, memory block, or display onto the infinite canvas. Resize, rotate, and label each part freely. Every component updates live as you work.

Connect Wires

Click any output pin and drag to an input pin to draw a wire. Wires auto-route around components. Multi-bit buses carry parallel signals, and signal tunnels link distant parts of a large circuit without clutter.

Simulate & Observe

Toggle inputs, drive a clock, and watch signal states propagate in real time. Attach an oscilloscope to any wire to record waveforms over multiple clock cycles. Export the circuit or share a live session link.

Learn digital logic basics

Who uses it

Built for learners and professionals

Students

Verify homework problems, explore truth tables, and build complete processor designs for coursework. Gate Lab's visual feedback makes abstract Boolean algebra tangible. It is a free Logisim alternative that runs entirely in the browser — no lab installation needed.

Educators

Share a pre-built circuit link so every student opens the same starting point instantly. Use the real-time collaboration feature to walk through a design live in class or during an online lecture. Save time grading by asking students to export and submit their .lgs files.

Engineers & Hobbyists

Prototype combinational and sequential logic before committing to hardware. Use programmable custom components to test novel architectures — ALUs, RISC CPU control units, custom memory controllers — and validate logic correctness before moving to an FPGA or PCB.

Examples

See what you can build

4-Bit ALU

Arithmetic logic unit

7-Segment Display

BCD decoder and display driver

8-Bit Counter

Synchronous binary counter

Custom 4×4 RAM

Addressable memory array

Matrix Display

Space invader dot-matrix

Keyboard Driver

PS/2 keyboard interface

4×4 Keypad Driver

Matrix keypad scanner

LCD Hello World

Character LCD controller

Help

Frequently asked questions

What is Gate Lab?

Gate Lab is a free, browser-based digital circuit simulator. You can drag and drop logic gates, connect wires, and watch signals propagate in real time — no installation required. It covers everything from basic Boolean logic to complex designs like ALUs, CPUs, and custom memory systems, making it ideal for students, educators, and engineers.

Do I need to install anything?

No. Gate Lab runs entirely in your web browser — just open the page and start building. It works in Chrome, Firefox, Edge, and Safari on desktop. No plugins, no downloads, no sign-up.

What components are available?

Over 40 component types across several categories:

Logic gates — AND, OR, NOT, NAND, NOR, XOR, XNOR (configurable input count)
Sequential logic — D/T/JK/SR flip-flops, 4/8/16-bit registers, 2/4/8-bit counters, shift registers
Data routing — multiplexers, demultiplexers, encoders, decoders, tri-state buffers, signal tunnels, buses
Arithmetic — adders, comparators
Memory — 128×4 and 128×8 RAM with built-in editor, ROM
I/O & displays — 7-segment display and decoder, character LCD, 64×64 matrix display, clock generator
Instrumentation — 1/2/4/8-channel oscilloscope
Custom — fully programmable components via scripting

How do custom programmable components work?

Custom components use Gate Lab's built-in scripting language to define any logic you need. You declare input and output pins, then write combinational logic or clocked sequential behavior with internal state variables. This lets you build anything beyond the standard library — from a custom ALU operation to a complete processor control unit — and reuse it as a component anywhere in your circuit.

Can I collaborate with others?

Yes. Gate Lab supports real-time multiplayer collaboration. Share your session link and others can join instantly — no account needed. Everyone can place components, draw wires, and run the simulation together, with each participant's cursor visible to the group.

Can I use Gate Lab to learn computer architecture or design a CPU?

Yes. Gate Lab includes every primitive you need to build a working processor: multi-bit adders and comparators for the ALU, RAM and ROM for instruction and data memory, registers for the register file and program counter, multiplexers for the data path, and programmable custom components for the control unit. The included sample circuit "4-Bit ALU" is a good starting point — it shows how to combine an adder, a logic unit, and a function-select multiplexer into a single arithmetic unit. From there, add an instruction register, a program counter, and a simple state machine for fetch-decode-execute, and you have a minimal working CPU running inside your browser.

Design circuits. Simulate logic.