The Adafruit Feather form factor boards are made to be stackable and have built-in support for 3.7V LiPo batteries with a charging circuit. The FEZ Feather provides both through hole pads and castellated edges making it both breadboard friendly and easy to build into products.
User LED PE11 WiFi SPI = SPI3 IRQ = PB12 CS = PD15 EN = PA8 RST = PB13 Buttons LDR = PE3 APP = PB7