Circuit Builder

Build real circuits on a breadboard and watch them come alive! A live simulator calculates every voltage and current as you build, so LEDs glow, capacitors charge and chips actually run. Nothing ever burns out, so go wild. Features 🔌 40+ parts: LEDs, transistors, 555 timers, logic chips, speakers and more 🤖 Program an Arduino Nano or ESP32 in C++ or Lua 🎹 14 examples: synths, Happy Birthday, Pong, Bad Apple!! and a calculator with zero microcontrollers 📈 Scope, voltage and current views, lights-off mode 🌍 Share builds in Community, chat and spectate your lobby 💾 Save up to 5 designs Controls WASD move · Q/E up and down · Shift faster · Hold right mouse to look 1 Select · 2 Hand (press buttons, turn knobs) · 3 Scope · 4 Wire Click to place · R rotate · [ ] change values · Delete remove · Ctrl/Cmd+Z undo · Esc cancel Stuck? Open the book icon for examples!