Live at velxio.dev

An open-source multi-board emulator and circuit simulator. Write Arduino C++, MicroPython, ESP-IDF or Python, compile it, and run it against real CPU emulation with 150+ interactive electronic components — all in your browser.

40 boards · 5 CPU families: AVR8 (ATmega / ATtiny), ARM Cortex-M (RP2040 / RP2350 / STM32), Xtensa LX6/LX7 (ESP32 / ESP32-S3), RISC-V (ESP32-C3 / ESP32-C6) and ARM Cortex-A Linux (Raspberry Pi Zero to 5).

Velxio is free and open-source. Building and maintaining a full multi-board emulator takes a lot of time — if it saves you time or you enjoy the project, sponsoring me directly helps keep development going.

Your support helps cover server costs, library maintenance, and frees up time to add new boards, components, and features. Thank you!

These companies have supported Velxio and provided their hardware so their components can be emulated accurately:

_{The DFRobot and M5Stack links above are affiliate links: a purchase made through them earns Velxio a small commission at no extra cost to you, and it helps pay for the hosted instance. The simulator itself is AGPL and free either way.}

Their hardware is in the catalog today: the M5Stack Cardputer and Core, the Pimoroni Badger 2350 and Galactic Unicorn, the Seeed Studio XIAO family and Grove modules, the DFRobot UNIHIKER and Gravity sensors, and the whole Espressif ESP32 line up to the ESP32-C6. Of these, the M5Stack, Pimoroni and DFRobot boards, the Seeed XIAO Sense, C6 and RP2040, and the ESP32-C6 DevKit are only available online at velxio.dev; the self-hosted image ships the Arduino, Raspberry Pi Pico and ESP32 families (see Supported Boards).

https://velxio.dev — no installation needed. Open the editor, write your sketch, and simulate directly in the browser.