Mokxi and Proteus, compared fairly
Mokxi is a free Proteus alternative for microcontroller simulation. It runs Arduino, ESP32, Pico and STM32 sketches against a circuit in your browser, with nothing to install and no license.
Last checked September 2026
- 505parts on the bench
- 45boards running now
- 1.00xreal time, on every board
Proteus is a commercial, paid tool from Labcenter Electronics with a SPICE-based analog simulator, a firmware-running VSM feature and full PCB design, aimed at embedded engineering education and professional work. It runs on Windows. Mokxi is a free, browser-based firmware simulator with a real breadboard. Here is where each one is the right answer.
The Mokxi editor running an Arduino Uno weather station, with the LCD showing the reading and the serial monitor printing it live.
Where Proteus leads
These are the strongest reasons to choose Proteus today.
- VSM genuinely combines SPICE-based analog simulation with real microcontroller firmware execution in the same schematic.
- Full schematic capture and PCB layout in the same product, carrying a design from a breadboard idea through to a board you can send for fabrication.
- Long established in embedded engineering courses and professional workflows, with the depth of analog modeling that a serious design needs.
- Labcenter lists more than 750 supported microprocessor variants, far past the boards Mokxi models.
Where Mokxi leads
These are working parts of Mokxi you can open and test for yourself.
- Free, with no license to buy, and running entirely in a browser tab with nothing to install, including on a Mac or a Chromebook.
- A real breadboard on a 0.1 inch grid rather than a schematic-first workflow, which suits wiring a project the way a beginner or a maker actually builds one.
- Your C++ is built by a real clang and the firmware runs on Mokxi’s own AVR, Xtensa, RISC-V and ARM Cortex-M cores across 42 boards, in the tab, with no license or install step.
- SPICE decks run in the editor, on an engine checked against ngspice. There is no PCB design at all: Mokxi stops at the breadboard and the firmware.
Side by side
Last checked September 2026. If anything here has gone stale, that is our mistake and we want to know.
| Mokxi | Proteus | |
|---|---|---|
| Aimed at | Makers and firmware work | Embedded engineering and PCB design |
| Price | Free; paid plans for classes and more room | Paid, commercial license; a free demo runs the sample designs |
| Runs in | A browser tab | A Windows desktop install |
| Analog depth | Nodal analysis on the canvas; SPICE decks with .op, .tran, .ac, .dc, .tf, .noise and .meas | SPICE-based mixed-mode simulation (VSM) |
| PCB design | No | Yes |
Which one should you use
Straight answers. Where the other one is the right call, we say so.
You need a free tool to try a sketch in a browser tab today
Mokxi.
You need SPICE-based analog simulation around the firmware, or a chip family Mokxi does not model
Proteus, not Mokxi.
You need to take a design through to a fabricated PCB
Proteus. Mokxi has no PCB tools at all.
You want an ESP32 or a Raspberry Pi Pico with no license to buy
Mokxi.
Looking for a free Proteus alternative?
Most people who search for one want to run a microcontroller sketch against a circuit without a Proteus license: an Arduino course, a student project, a first go at an ESP32. For that job Mokxi is free, runs in a browser tab with nothing to install, and compiles the sketch in the page.
For the other things Proteus is bought for, it is not a replacement. Mokxi’s SPICE engine has no vendor model libraries or BSIM MOSFETs, Mokxi has no PCB layout, and it does not cover Proteus’s range of chip families. If your course or your work depends on those, stay with Proteus.
Compare the other options
The same straight comparison for the tools teachers, students and makers also consider.
In short
Is there a free alternative to Proteus for Arduino simulation?
Yes. Mokxi simulates the Arduino Uno, Nano, Mega, Leonardo and Uno R4, among other boards, on its free plan, running the compiled sketch in your browser.
Should I use Mokxi if you need a free tool to try a sketch in a browser tab today?
Mokxi.
Should I use Mokxi if you need spice-based analog simulation around the firmware, or a chip family mokxi does not model?
Proteus, not Mokxi.
Should I use Mokxi if you need to take a design through to a fabricated pcb?
Proteus. Mokxi has no PCB tools at all.
Should I use Mokxi if you want an esp32 or a raspberry pi pico with no license to buy?
Mokxi.
Try it yourself
A comparison page is somebody else’s opinion. Open the editor, press Run and make up your own mind.