Run your sketch without a board
This really runs your code. Change the numbers, press Run, and the virtual LEDs, buzzer, servo and Serial Monitor react exactly like the real thing — nothing can break and nothing can shock you.
Try this: Pin 13 turns on and off once a second. Watch LED 13 in the board panel.
simulator.ino
Serial Monitor0 ms
Press Run — anything you Serial.println() appears here…