Logic gate simulator

digiwleea is a free, online logic gate simulator that runs in your browser. Drop in gates and transistors, draw wires between their pins, flip an input, and watch the signals light up across the circuit in real time. No sign-up, no install, and it is made for students learning how digital logic actually works.

What you can do with it

• Build gates from transistors. This is a switch-level simulator, so you wire NMOS and PMOS transistors into real CMOS gates and see why each one is shaped the way it is.
• Watch signals flow. Wires are colored by their state: high, low, floating, or shorted. Flip an input switch and the change ripples through the circuit instantly.
• Read the truth table. One click sweeps every input combination and prints the full truth table for your circuit.
• Plot timing waveforms. Add a clock and the simulator runs the circuit forward over many cycles, drawing a logic-analyzer style timing diagram so you can debug sequential logic like counters and registers.
• Save and reuse parts. Turn any working circuit into a library part, then compose adders, multiplexers, registers, and eventually a whole CPU.

Why it is free and in your browser

The simulator runs entirely on your own machine as a web app, so there is no server to pay for and nothing to download. That keeps it free, fast, and private: your circuits stay in your browser unless you choose to sign in and sync them. It works on a laptop, a tablet, or a phone, and you can even install it to run offline.

It is built for students. The same tool that draws a single NOT gate scales up to a working 8-bit processor, so you can start at A AND B and end at fetch, decode, execute without ever switching apps.

How to use it

• Open the lab and grab a part from the parts bin on the left: an input switch, a transistor, or a gate.
• Pick the wire tool (W) and connect pin to pin to wire your circuit together.
• Click an input switch to toggle it between 0 and 1, and watch the wire colors update across the circuit.
• Press the Truth Table button to compute the full table, or the Waveform button to run a clock and plot the signals over time.
• Happy with it? Use Add to Library to save your circuit as a reusable part you can drop into a bigger design.

Example: an AND gate from two NMOS transistors

Suppose you want to see an AND function from first principles. Place two NMOS transistors in series between an input source and the output, and tie their gates to two input switches A and B. Current only reaches the output when both transistors conduct, that is, only when A = 1 and B = 1. Flip just one input low and the path breaks, so the output drops. That is exactly the AND truth table: the output is 1 only on the last row. Click Truth Table and the simulator confirms it. From there, add a CMOS inverter on the output and you have built a NAND, the universal gate that every other gate can be made from. And if you are curious how the transistors themselves switch, one level deeper, watch it in the interactive MOSFET simulator.

Frequently asked

Is this logic gate simulator free?

Yes. The simulator runs entirely in your browser at no cost, with no sign-up and nothing to install. You can build, save, and share circuits for free.

Do I need to install anything to simulate logic gates?

No. It is a web app, so it works in any modern browser on a laptop, tablet, or phone. There is no download and no plugin. You can also install it as an offline app if you want.

Can I build gates from transistors?

Yes. This is a switch-level simulator, so you wire NMOS and PMOS transistors into CMOS gates and watch them work, then save each gate as a reusable part and compose larger circuits like adders and registers.

Does it show a truth table?

Yes. One click computes the full truth table from your circuit's inputs and outputs. For circuits with a clock you can also plot every signal over time as a timing waveform.