Velxio 2.0 – Emulate Arduino, ESP32, and Raspberry Pi 3 in the Browser

Velxio 2.0 is live.

A free, open-source emulator for 19 embedded boards: Arduino, ESP32, Raspberry Pi, RISC-V , running real compiled code in your browser.

The best part: it's fully local.

No cloud dependency. No student accounts. No data leaving your network. Self-hostable with a single Docker container.

Universities and bootcamps can deploy it on their own servers and give every student access to a complete embedded development environment, for free.

I've been working on this for over a year, and just shipped v2.0 with ESP32 emulation (via QEMU), a custom RISC-V core, and Raspberry Pi 3 support that runs real Python

Hey HN, I posted Velxio here a while back and got great feedback. Since then I've shipped a major update

What's new in v2:

- 19 boards across 5 CPU architectures (AVR8, Xtensa, RISC-V, ARM Cortex-M0+, ARM Cortex-A53) - ESP32 emulation via QEMU (lcgamboa fork) — real flash images, ROM function emulation, GPIO/ADC/timers - ESP32-C3 and CH32V003 run on a custom RISC-V core written in TypeScript, entirely in the browser - Raspberry Pi 3B via QEMU raspi3b — boots real Pi OS, runs Python - Realistic sensor simulation: DHT22 (40-bit protocol timing), HC-SR04 (trigger/echo), WS2812B NeoPixel (GRB decoding) - 48+ electronic components from wokwi-elements

Architecture:

- AVR, RP2040, and RISC-V emulation runs client-side (avr8js, rp2040js, custom TS core) - ESP32 Xtensa and Pi 3 run on backend QEMU - Compilation via real arduino-cli - React + Vite frontend, FastAPI backend - Self-hostable via Docker, no account needed

Source: https://github.com/davidmonterocrespo24/velxio (AGPLv3)

Happy to discuss the emulation architecture — particularly the trade-offs between in-browser vs. backend QEMU emulation

Quick update: traffic is still coming in waves, had to scale up compilation workers to keep up with demand

Things are more stable now, but still tuning performance under load

If anyone finds it useful, the source is here: https://github.com/davidmonterocrespo24/velxio

Always happy to get feedback or contributions.

Pretty cool project! if you're checking it out, try one of the built-in examples and hit "Compile + Play". It runs immediately, no setup required

I often write a bunch of Esphome ‘code’ , which I then use with various esp32 based devices (mostly from M5stack) via esphome/HomeAssistant.

Can this project help me in any way during dev stage before uploading the code to device just to see it doesn’t work ? Eg could I use this to somehow compile&run those esphome yamls via this emulator?

Can someone who has used both wokwi and this do a compare/contrast? The footer suggests that it's built on top of wokwi-elements

The container instructions has `-d` in it, but note that after booting the container it downloads another, I don't know, 300+mb more (its still downloading as I write), so if you can't connect that's why.

Might be better to not include `-d` in the instructions?

First of all: Awesome work! Playing with it now.

One suggestion: The main splash screen image is nearly 8MB big. It takes a noticeable time to download on my connection. I'm not sure what bandwidth costs these days, but seems like that could be something to optimize.

Nice work! One minor point for me: it wasn’t immediately clear that you need to press Compile before Play gets enabled (e.g. Arduino IDE let's you upload right away and compiles if needed)

This is fantastic. I am doing my first-ever consumer electronics product and this would save a lot of soldering time

This is a great idea. It’s always been inconvenient requiring access to the physical board just to be able to test these sort of projects.

Awesome. Is there any chance of getting MicroPython or CircuitPython support?

I like this Idea but I don't want to use this. I know what kind of prompt U using to create this one: "Create something like Wokwi and make it local"

Abang

Great project! Now all there is left to do is a VS Code plugin. Also make it play nice with platform io.

[dead]

[dead]