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
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.