was a web-based electronic design automation (EDA) tool developed by Autodesk. It functioned as a comprehensive platform for hobbyists, students, and makers to design, simulate, and fabricate printed circuit boards (PCBs).
The standout feature: . You could write Arduino code in a web-based IDE, attach it to a virtual Uno, and watch LEDs blink, servos turn, or serial output appear – all without hardware. This wasn’t just a SPICE simulator; it was a microcontroller emulator. For learning, this was gold. You could debug logic errors before soldering a single joint. 123d circuits
Drag and drop components onto a digital breadboard to see how they connect physically. was a web-based electronic design automation (EDA) tool
123D Circuits was an admirable, ahead-of-its-time attempt to democratize PCB design. It lowered the barrier to entry and taught thousands of makers how to go from blinking an LED in a simulation to holding their own fabricated board. But in 2026, it is a ghost town – a museum piece you can occasionally glimpse via archived URLs. For new projects, look to its successors. For nostalgia, pour one out for the little browser PCB tool that tried to fly. You could write Arduino code in a web-based
For users seeking a similar experience today, the closest alternatives include: