Circuito.io - Instant code and wiring for your project
PlatformIO - Next-generation IDE for IoT
B4R - Development tool for native Arduino programs.
embedXcode - embedXcode is a template for Xcode.
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation
InstaPart - Build circuit boards faster with parts delivered in <24 hrs