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Build circuits that run,
right in your browser.

Mokxi is a free electronics simulator for Arduino, ESP32, Pico and STM32, in your browser.

Start freeOpen the editor

Open or drop a Wokwi, Fritzing or .ino file to get startedImport
Stackerlive0.000 s 0.00x
++−−++−−jjiihhggffeeddccbbaa115510101515202025253030ESP32-C3MINI-1ESP32-C3-DevKitM-1GND3V33V323RSTGND0110456785V5VGNDGND918192021NCNCNCNCNCNCRGB8BOOTRST12MAX7219MAX7219
Real ESP32-C3 firmware. Click to open it and play.
Open in the editor

Students at 84 schools build with Mokxi

“I’d been looking for a real online electronic simulator that was intuitive and complete when I found Mokxi. I was able to quickly import a Fritzing file and my Arduino sketch and start testing. Mokxi has all of the makings for the best online Arduino simulator I have been able to find!”

JayModel builderFeatured in his DioramaOS post

503 parts

On 44 boards: Arduino, ESP32, Pico, STM32 and more, each part drawn by the code that simulates it.

makers

Students, teachers and tinkerers building on Mokxi, free to start.

969 projects

Built in and ready to open, from a first blink to a game console.

Mokxi in action

From the first wire to a board on your desk.

  1. Wire it the way you would on the bench.

    Drag parts onto a breadboard and run each wire from pin to pin. Every part is drawn by the same code that simulates it.

    Learn more

  2. Press Run and watch the real firmware.

    Your sketch compiles in the tab and runs on a model of the chip, with a serial monitor, a plotter and a scope.

    Learn more

  3. Take it off the screen.

    Send the sketch to a real board, or lay the circuit out as a PCB with its Gerbers and parts list. Those come with Pro, and the trial has them.

    Learn more

“The AI checker helps check and correct my circuits, and it has way more components than Tinkercad. As a student I really appreciate the tool.”

ChloeEngineering student
A traffic light circuit wired on a breadboard beside an Arduino Uno.
The problem

Your circuit isn’t failing
because of you.

Most first circuits fail on the bench for small reasons: an LED with no resistor, a pin that is never set, a button left floating, a short to ground. Mokxi’s Checkup and Kix AI check read your circuit and your code and name each one, with the fix, before you buy a single part.

Kix AI check
A breadboard with a pushbutton in the editor, the circuit the example Checkup reads.Problem found
Your circuit Checked2 issues
4 of 6 checks pass
  • Supply not shorted to groundOK
  • Grounds joinedOK
  • pinMode setOK
  • Serial.begin calledOK
  • LED has a resistorNo resistor on pin 13
  • Button pin pulledPin 2 floats

Parts OK

Arduino UnoBreadboardPushbutton

Fix these

LED on pin 13Button on pin 2

Runs on Arduino Uno · ESP32 · Raspberry Pi Pico · STM32 · ATtiny85

Your bench

Everything in the parts bin

Here's every part waiting for you, each one drawn by the very code the editor runs.

Full-size breadboard
A real 0.1 inch grid with the rails and the center channel, 63 columns wide.
Jumper wires
Drag from any pin or hole to any other. Corners snap, and you can drag them.
Power
A supply rail at the voltage you choose.
Ground
The other end of every circuit.
LED
Lights when current flows. Five colors, and the brightness is what your eye would see.
Filament lamp
A tungsten bulb in a holder: an inrush when it is switched on cold, tens of milliseconds to warm up, and dim on half its voltage.
Resistor
Any value you like, with the color bands drawn to match.
ESP32-C3-DevKitM-1
A RISC-V board that runs your firmware at 160 MHz on the real memory map.
Pushbutton
A 12 mm tactile switch. Hold it while the simulation runs.
Raspberry Pi Pico
The RP2040 board on our own Cortex-M0+ core. Pick a program and press Run.
Raspberry Pi Pico W
Raspberry Pi Pico W (RP2040). The same board and the same pinout as a Pico, with the CYW43439 on it. The WiFi is simulated (no radio; real internet through the Cloud panel’s switch), and the on-board LED, which hangs off that chip rather than off GP25, is driven through the same path. Everything else is the Pico.
Raspberry Pi 4 Model B
Raspberry Pi 4 Model B: the 40-pin header, driven by main.py with RPi.GPIO or gpiozero.
See every part
Boards

Real boards, built from the datasheets

Each board has its own memory map. Open its page to see what runs here, what transfers to hardware, and what the model does not cover yet.

ESP32-C3-DevKitM-1

A RISC-V chip at 160 MHz, on the real memory map.

Open the board page
Arduino Uno R3

The classic Arduino, with an ATmega328P running at 16 MHz.

Open the board page
Arduino Nano

The Uno’s chip on a small board that fits a breadboard.

Open the board page
Arduino Mega 2560

The big Arduino, with 54 digital pins and four serial ports.

Open the board page
Arduino Leonardo

An Uno-shaped board whose chip does its own USB serial.

Open the board page
ESP32-C6-DevKitC-1

A second RISC-V board, with 31 pins and simulated WiFi.

Open the board page
ESP32 DevKit V1

The classic ESP32 at 240 MHz, with simulated WiFi.

Open the board page
ESP32-S3-DevKitC-1

The ESP32-S3 at 240 MHz, with USB serial and an RGB LED.

Open the board page
All 40 boards

Compiles in your browser. No build queue. How fast, measured

Plans

Start free, go Pro when you build for real.

Every board, every part and the simulator are free. Pro adds sending to a real board, clean pictures, private projects and more of Kix every day.

Compare all plans

“I’m using Mokxi to develop and simulate an STM32-based four-wheel-drive robot car before building the actual hardware. It allows me to experiment with DC motor control, PWM, RPM measurement using photointerrupters, and different acceleration, braking, and reversing strategies, helping me understand and refine the system before implementing it in real life.”

NusretRobot car builder, Hamburg
ProMost popular
$7.99/ month

For when you build it for real.

  • Everything in Free, plus:
  • Upload to your real board
  • Schematic and PCB ordering
  • Clean pictures, no badge
  • Unlimited private projects
  • Works offline
  • Kix AI every day
  • EE lab and exam prep
  • Commercial use

14-day money backSecure checkout by Stripe

Free
$0forever

For anyone learning electronics.

Start free
  • Unlimited building and simulation
  • Every board and part
  • 10 public projects
  • 5 questions to Kix AI a day
  • Real internet for WiFi boards

or try it without an account

Projects

Start from a project that already works.

Games77 projectsLights349 projectsSound129 projectsSensors339 projectsMotors182 projectsDisplays246 projectsControllers183 projectsIoT43 projectsAnalog55 projectsView all ›969 projects to start from

“The AI checker helps check and correct my circuits, and it has way more components than Tinkercad. As a student I really appreciate the tool.”

ChloeEngineering student

Simulate any board, from an Uno to an ESP32-S3.

Each board runs its own compiled firmware on a model built from the datasheet, with its own memory map, timers and pins.

Learn more
An Uno playing a sine wave through a DAC, with the scope open.

Ask Kix AI when it will not behave.

Kix reads your circuit and your code, explains what it does, and suggests a fix you can apply in a press.

Learn more
Kix AI open beside a traffic light circuit.

Export a real PCB when it works.

Lay the circuit out as a board, route it and check it, then take the Gerbers, drill file and parts list to a fab house.

Learn more
A binary clock laid out as a PCB beside its breadboard.

Teach a class with lessons that check themselves.

Give a class starter circuits and step-by-step lessons the simulator checks as students wire, and see who is stuck.

Learn more
The first lesson in the editor: the steps on the left, the breadboard beside them.
Reviews

What makers say about Mokxi

“The AI checker helps check and correct my circuits, and it has way more components than Tinkercad. As a student I really appreciate the tool.”

ChloeEngineering student

“I’d been looking for a real online electronic simulator that was intuitive and complete when I found Mokxi. I was able to quickly import a Fritzing file and my Arduino sketch and start testing. Mokxi has all of the makings for the best online Arduino simulator I have been able to find!”

JayModel builderFeatured in his DioramaOS post

“I’m using Mokxi to develop and simulate an STM32-based four-wheel-drive robot car before building the actual hardware. It allows me to experiment with DC motor control, PWM, RPM measurement using photointerrupters, and different acceleration, braking, and reversing strategies, helping me understand and refine the system before implementing it in real life.”

NusretRobot car builder, Hamburg
Share your story
On your phone

The same editor, in your pocket.

Drag a part, run a wire and hold a button with one finger. Mokxi runs right in your phone’s browser, with the same account and projects.

Open the editor
The Mokxi editor on a phone: an Uno blinking an LED, with its sketch under the circuit.
Ring Simon on an ESP32-C3 in the editor on a phone, in the light theme.
The help panel on a phone, with Ask Kix at the top.
In brief

What Mokxi is

Mokxi is a free electronics simulator that runs in your web browser. Wire a breadboard, write C++ firmware and press Run, even on a school Chromebook.

  • Runs in your browser
  • No install, no account to start
  • Every board and part free

Simulators

Teachers and schools

Start learning

Every board (44)

Compare all boards
Arduino
ESP32 and ESP8266
Raspberry Pi
STM32
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