Free online circuit simulator with Arduino-style code.
Drag parts onto a grid, route wires, drive an Arduino Uno from a sketch, probe with a multimeter or oscilloscope. Real DC + transient simulation under the hood — LEDs light at the right current, capacitors charge on a real RC curve, parts can burn out if you wire them wrong. No install. No Spice. Just a browser tab.
No install · No credit card · Works in any modern browser
What's inside ExoSynk Lab
A real workbench — same parts and instruments you'd use on a real breadboard, simulated honestly.
Schematic editor
Drag from a parts palette, snap to grid, route wires with junction dots and hops. Full keyboard shortcuts. Auto-simulates as you change the circuit.
DC + transient simulation
Modified Nodal Analysis solves Ohm/KCL/KVL exactly. The transient solver follows capacitor charge curves, RC time constants, and time-varying inputs.
Arduino-style code
Place an Arduino Uno and drive it from a sketch: pinMode, digitalWrite, analogRead, analogWrite (PWM), delay, Serial. Sketches are written in JavaScript syntax — compiling real Arduino C++ is on our roadmap. Pins drive simulated LEDs and read simulated voltages in real time.
Multimeter + oscilloscope
Read every node voltage and every part's current. Add as many scope probes as you need to watch signals over time. A voltage-gradient overlay paints the whole circuit so you can see where charge is flowing.
Honest parts library
Resistors, capacitors, inductors, LEDs, diodes, transistors, MOSFETs, switches, relays, 555 timer, op-amps, logic gates, buzzers, 7-segment displays and more. LEDs have real forward voltages and burn out above their rated current. Parts we don't model yet are clearly marked “Not simulated yet”.
Why use an online circuit simulator?
Most electronics projects fail on the breadboard for predictable reasons — wrong resistor on an LED, a transistor wired backwards, a capacitor charging through the wrong path. ExoSynk Lab lets you catch those mistakes in the browser before you ever pick up a soldering iron. It runs the same physics a real circuit does, then shows you the answer: current through every wire, voltage on every node, and which parts are about to burn.
Built for Arduino projects
Drop an Arduino Uno on the grid, wire an LED and resistor to pin 13, write digitalWrite(13, HIGH), and the LED lights at the current its forward voltage and resistor allow — wire it wrong and it burns out. Sketches use the familiar Arduino functions (pinMode, digitalWrite, analogRead, analogWrite, delay, millis, Serial) written in JavaScript syntax, so blink, button reading, PWM dimming and serial output all work. Compiling real Arduino C++ is on our roadmap.
Frequently asked questions
Is ExoSynk Lab free?+
Yes. The 2D circuit lab, code panel, multimeter, and oscilloscope are all free. You need a free account to open the lab and save your labs.
Do I need to install anything?+
No. ExoSynk runs entirely in the browser — nothing to install, no toolchain to configure. Works on any modern browser: Chrome, Edge, Firefox, Safari.
Can I program a microcontroller?+
Yes — place an Arduino Uno and drive its pins from a sketch. Sketches use the familiar Arduino functions (pinMode, digitalWrite, analogRead, analogWrite, delay, millis, Serial) but are written in JavaScript syntax, e.g. function setup() { … }. Compiling real Arduino C++ is on our roadmap.
Is the simulation real or just animation?+
Real. ExoSynk uses Modified Nodal Analysis for DC simulation and a transient solver for time-varying circuits. LEDs light at their correct current, capacitors follow RC curves, and parts can burn out. A few parts in the palette are marked "Not simulated yet" — those don't affect the circuit.