void setup() { pinMode(13, OUTPUT); Serial.begin(9600); }

void loop() { digitalWrite(13, HIGH); Serial.println("LED ON"); delay(500);

  digitalWrite(13, LOW);
  Serial.println("LED OFF");
  delay(500);

In Velxio you can connect an LED to pin 13 and watch it blink, while the Serial Monitor prints the messages in the terminal.

A fully local, open-source Arduino emulator. Write Arduino code, compile it, and simulate it with real AVR8 CPU emulation and 48+ interactive electronic components,All running in your browser. GitHub: https://github.com/davidmonterocrespo24/velxio

The goal of this project was to learn more about how emulators work internally: CPU instructions, memory management, and low-level architecture.

It's still experimental, but it already runs basic instructions and I'm continuing to improve it.

[Edit] Which also does Arduino.