Emulate Arduino and ESP32 in your browser

A tiny board like an Arduino is basically a stripped-down computer that runs one program over and over, usually to read a sensor or flip a pin on and off. An ESP32 does the same job with more horsepower, adding built-in Wi‑Fi, Bluetooth, and faster processors for things like web servers and connected gadgets. (velxio.dev) The hard part is that embedded programming usually starts with a pile of physical stuff: a board, a cable, drivers, a compiler, and at least one wrong wire. Velxio’s pitch is that you can skip that first shopping trip and run the board, the code editor, and the circuit simulator inside one browser tab. (velxio.dev) What makes that possible is emulation, which means software pretending to be the chip itself instruction by instruction, like a piano app replaying every key press instead of just showing a picture of a keyboard. Velxio says it emulates 19 boards across 5 processor families, including Arduino Uno, ESP32, ESP32‑C3, Raspberry Pi Pico, and Raspberry Pi 3. (velxio.dev) Those boards are not all the same kind of machine. Velxio lists classic Arduino boards on AVR8 chips, Raspberry Pi Pico boards on the RP2040 chip, ESP32‑C3 boards on RISC‑V, standard ESP32 boards on Xtensa, and Raspberry Pi 3 on 64‑bit Arm Linux. (velxio.dev) That last part matters because a Raspberry Pi Pico and a Raspberry Pi 3 are different categories of device. Raspberry Pi’s own documentation says the Pico is a microcontroller board programmed by flashing code into onboard memory, while the Raspberry Pi 3 is a full Linux computer. (raspberrypi.com) (velxio.dev) Velxio says the browser app includes a code editor, a local compiler, a serial monitor, and more than 48 visual components such as light-emitting diodes, liquid crystal displays, servos, buzzers, ultrasonic sensors, and keypads. That means you are not just running code in a vacuum; you can wire up virtual parts and watch the outputs change on screen. (velxio.dev) The project’s GitHub page says the code is open source, and the site says it can run locally with no cloud services required for many boards. The same GitHub page also says you can self-host it with Docker, which is useful for classrooms, workshops, or companies that do not want student or prototype code sent to a third-party server. (github.com) (velxio.dev) Velxio is not arriving in an empty market. Wokwi already offers a browser simulator for Arduino, ESP32, STM32, and Raspberry Pi Pico projects, and Velxio’s own site credits tools like avr8js and wokwi-elements under the hood. (wokwi.com) (velxio.dev) The difference Velxio keeps pushing is breadth plus control. Its homepage says some architectures, including AVR8, RP2040, and ESP32‑C3, run fully in the browser, while standard ESP32 boards and Raspberry Pi 3 use QEMU-based backends for heavier emulation. (velxio.dev) That means this is best thought of as a fast front porch for hardware work, not a replacement for a bench full of real electronics. If your code fails in the emulator, you saved a board and an afternoon; if it passes in the emulator and fails on hardware, you have narrowed the problem down to wiring, timing, power, or a real-world quirk the browser cannot fake. (hackaday.com) (velxio.dev)