Velxio — Free Local Arduino Emulator
Editor Examples GitHub Discord Documentation

The free, open-source Arduino emulator that runs in your browser

Write Arduino code, compile it, and simulate it with real AVR8 CPU emulation and 48+ interactive electronic components — all running locally in your browser. No cloud, no latency, no account required.

Features

  • Real ATmega328p (AVR8) emulation at 16 MHz via avr8js
  • Raspberry Pi Pico (RP2040) emulation via rp2040js
  • 48+ wokwi interactive electronic components (LEDs, resistors, buttons, sensors…)
  • Monaco Code Editor with full C++ / Arduino syntax highlighting
  • arduino-cli compilation backend — produces real .hex / .uf2 files
  • Serial Monitor with auto baud-rate detection and send
  • Library Manager for Arduino libraries
  • Multi-file workspace (.ino, .h, .cpp)
  • Wire system with orthogonal routing
  • ILI9341 TFT display simulation
  • I2C, SPI, USART, ADC, PWM support
  • Docker standalone image — deploy anywhere with one command

Supported Boards

  • Arduino Uno (ATmega328p) — full AVR8 emulation
  • Raspberry Pi Pico (RP2040) — RP2040 emulation

Get Started

Open the Editor — no installation needed.
Self-host with Docker: docker run -d -p 3080:80 ghcr.io/davidmonterocrespo24/velxio:master

Documentation

Browse the full Velxio documentation to learn how to set up, configure, and extend the emulator:

  • Introduction — What is Velxio and why use it?
  • Getting Started — Hosted editor, Docker, and manual setup
  • Emulator Architecture — AVR8 and RP2040 CPU emulation internals
  • Components Reference — All 48+ interactive electronic components
  • Project Architecture — System design, data flows, and stores
  • Wokwi Libraries — avr8js, wokwi-elements, rp2040js integration
  • MCP Server — AI agent integration via Model Context Protocol
  • Project Status — All implemented features and troubleshooting
  • Roadmap — Implemented, in-progress, and planned features

Frequently Asked Questions

Is Velxio free?
Yes. Velxio is free and open-source under the GNU AGPLv3 license. A commercial license is available for proprietary integrations.
Does Velxio work offline?
The simulation engine runs entirely in the browser. Compilation requires the local arduino-cli backend. Self-hosted deployments work fully offline once running.
Is Velxio a Wokwi alternative?
Yes. Velxio is a free, self-hosted alternative to Wokwi. It uses the same avr8js and wokwi-elements open-source libraries but runs on your own machine.
What boards are supported?
Arduino Uno (ATmega328p / AVR8) and Raspberry Pi Pico (RP2040). More boards are planned.