Free digital logic tools and reference: truth tables, Karnaugh maps, boolean algebra, circuit diagrams, and a logic gate simulator called Logic Nodes.
Try it: logicgates.org, no account, no install. Straight to the tools, or to the simulator.
Simulation:
- AND, OR, NOT, XOR, NOR, and NAND gates
- Interval (clock), delay, counter, button, toggle, and display nodes for time-dependent circuits
- Tick-based propagation, so feedback circuits (SR latches and friends) behave deterministically
Algebra:
- Truth table generation from any circuit
- Boolean expression generation, with optional simplification (requires a Wolfram Alpha App ID)
- The reverse direction too: construct a circuit from a boolean expression or a filled-in truth table
Editor:
- Custom nodes: package any circuit into a reusable component
- Pan, zoom to cursor, undo/redo, copy/paste, layers, and a minimap (ctrl+m)
- Keyboard shortcuts (ctrl+/ for the overview)
- Save/load in the browser (localStorage, with autosave) and file import/export as JSON
- Copy a selection to the clipboard as JSON that pastes onto someone else's canvas
- Built-in examples open straight from a link, e.g.
/simulator#example:Calculator - Built-in examples, including a working four bit calculator
Most of the site is the reference and the tools; the editor is one page of it. Everything is statically prerendered from the same codebase:
- Learn: a guided path from one gate to a four bit adder, plus references for the six gates, their symbols, flip-flops, common circuits and the laws of boolean algebra.
- Tools: truth tables, boolean simplification, Karnaugh maps
with don't cares, SOP/POS, NAND/NOR conversion, Gray code, and a circuit diagram generator that
exports SVG, PNG, Verilog or VHDL. The truth table and circuit generators take several outputs at
once (
sum = a ^ b; carry = a & b), sharing inputs and any common gates. For logic class rather than circuits, there are also truth tables for logic statements (p → q, q ∴ p), which check tautologies, equivalence and argument validity. - Practice and a worksheet generator with an answer key, both driven by a seeded question generator, so a link reproduces the exact same questions with no account or database involved.
Every truth table, identity and gate count on those pages is generated by src/lib/boolean.ts and
checked by a property-based test suite, so the published content cannot drift from the maths.
pnpm install
pnpm dev # start the dev server
pnpm build # production build
pnpm test # playwright tests
pnpm og # regenerate the social cards (needs Chrome)
pnpm cards # regenerate the gate reference imagesThe whole editor is hand-written: rendering happens on a canvas with no diagramming library, and only the menus use Svelte. The interesting parts (viewport culling, high-DPI handling, hitboxes, the tick system) live in src/nodesystem/. I wrote up the lessons from building it here: Hand-writing a canvas node editor in TypeScript.
Built by Sem, a freelance software developer. There's a short project page on my site as well. The site is LogicGates.org; Logic Nodes is the name of the canvas editor it ships.
Licensed under Apache 2.0.