ATMEGA328P-AU Microchip 8-Bit MCU (TQFP-32)

Rather than buying a finished Arduino board and either using its full footprint or desoldering the chip off it, this bare ATMEGA328P-AU puts the exact same genuine Microchip silicon that powers the Arduino Uno and Nano directly in a builder's hands, in the compact TQFP-32 surface-mount package meant for a custom board layout. It's the right starting point for anyone designing their own Arduino-compatible board from scratch rather than building around an existing one.