PlatformIO - Next-generation IDE for IoT
ThingSpeak - Open source data platform for the Internet of Things. ThingSpeak Features
B4R - Development tool for native Arduino programs.
Beebotte - Beebotte is a cloud platform providing key building blocks to accelerate the development of the...
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation
AskSensors - The easiest IoT platform