The best ESP32 simulator for what you are building

Two free browser simulators run real ESP32 firmware today: Wokwi and Mokxi. Wokwi covers the widest range of ESP32 chips and languages, with simulated WiFi that reaches the internet. Mokxi runs eleven ESP32 boards with your Arduino code compiled in the browser tab, beside analog circuits, bench instruments and a class workflow. Tinkercad Circuits, the most common classroom simulator, has no ESP32 at all.

We make Mokxi, so we have a stake. Every claim about another tool here comes from the sources at the bottom of the page, each with the date we last checked it, and where another tool is the better answer the page says so. The circuit above is an ESP32-C3 serving a web page that switches an LED: press Run and the serial monitor prints “open http://192.168.4.2/ in the Web tab”.

Wokwi lists ten ESP32 chips on Xtensa and RISC-V, three of them in alpha or beta, alongside the AVR Arduino boards, STM32 parts, the ATtiny85 and the Raspberry Pi Pico. That is the broadest ESP32 range of any simulator we know of.

Mokxi runs eleven ESP32 boards on its free plan: the ESP32 DevKit V1 and DevKitC V4, the LOLIN32 Lite, the ESP32-S3-DevKitC-1, the ESP32-C3-DevKitM-1 and C3 SuperMini, the ESP32-C6-DevKitC-1, the Arduino Nano ESP32, and the Seeed XIAO ESP32-C3, C6 and S3, plus three ESP8266 boards. Each board page lists what is covered and what is not.

Wokwi runs Arduino, ESP-IDF, MicroPython, CircuitPython and Rust on the ESP32, and builds sketches on its servers; on the free plan, users have reported waits for a busy build server on its public tracker.

Mokxi runs Arduino C++, and MicroPython on the Raspberry Pi Pico. A real clang inside the browser tab compiles the sketch, so there is no build server and no queue: the first build in a fresh browser downloads the compiler once, and later builds take about a second. More than 100 common Arduino libraries are built in, and you can add your own as a zip on every plan.

Projects move from Wokwi to Mokxi in one step: paste a Wokwi project link, or drop its diagram.json and sketch or its zip, on Mokxi’s import page. The parts, the wiring and the sketch come across, and a report lists anything that did not map and which libraries are built in or missing. Going back is as easy, since Mokxi’s Export menu writes a Wokwi project zip. A project built on MQTT, ESP-IDF, MicroPython on an ESP32 or a Wokwi custom chip should stay on Wokwi, because Mokxi has no equivalent for those today; a MicroPython project for the Raspberry Pi Pico comes across and runs.

Moving from an Uno to an ESP32 in either tool means the same three changes. The pin numbers become GPIO numbers. The pins run at 3.3 V, so a 5 V sensor output needs a divider or a level shifter on the way in. And analogRead returns 0 to 4095 instead of 0 to 1023, so any formula that assumes 1023 needs the new number.