Build logic circuits in your browser
A free logic gate simulator for students, hobbyists, and anyone learning digital logic. Wire up gates, watch the signals flow, and read off the truth table.
Free and open source. No account, nothing to install.
Hand-written TypeScript on an HTML5 canvas.
A live half adder. Take over by clicking the inputs.
| A | B | sum | carry |
|---|---|---|---|
| 0 | 0 | 0 | 0 |
| 0 | 1 | 1 | 0 |
| 1 | 0 | 1 | 0 |
| 1 | 1 | 0 | 1 |
What it can do
AND All the basic gates
AND, OR, NOT, XOR, NAND, and NOR, plus clock, delay, counter, button, toggle, and display nodes for interactive, time-dependent circuits.
0 1 Truth table generator
Build a circuit and read off its complete truth table. It works the other way too: fill in a truth table and the simulator constructs a working circuit from it.
A·B Boolean expressions
Turn any circuit into its boolean formula, or paste an expression and get a circuit back. Optional simplification through the Wolfram Alpha API.
+ Custom nodes
Package a circuit into a reusable component. Build a half adder once, then drop it into bigger designs, up to counters and registers.
URL Share with a link
Circuits encode into the URL, so sharing your work is copy-paste. Saves live in your browser, with file export and import. Nothing is uploaded.
undo Proper editor tools
Pan, zoom to cursor, undo and redo, copy and paste, layers, a minimap, and keyboard shortcuts (ctrl+? shows the list). Built-in examples include a working calculator.
How to use it
- Add gates. Right-click the canvas (or use the toolbar) and pick a node: start with a button, a couple of gates, and a display.
- Wire them up. Drag from a node's output point to another node's input. Signal states show live: high, low.
- Experiment. Toggle the inputs and watch the circuit respond. Then generate the truth table and see your circuit as algebra.
Made for learning digital logic
Logic Nodes started as a way to understand logic gates properly and grew into a full circuit editor. It's well suited for boolean algebra homework, building an SR latch or a half adder for the first time, or experimenting with feedback and clocks. Teachers can share example circuits with a link, and students need nothing but a browser.
The editor, with one of the built-in examplesQuestions
Is it free?
Yes. Free, open source under Apache 2.0, and it runs entirely in your browser. No account, no tracking.
Where are my circuits saved?
In your own browser (localStorage), with file export and import if you want backups. Nothing is uploaded to a server.
Can I share circuits?
Yes, a circuit can be encoded into the page URL. Sharing a circuit is sharing a link.
Ready to build something?
Open the simulatorThe built-in examples include a working calculator. Start from one of those if a blank canvas feels like a lot.