Arduino IDE - Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware...
ThingSpeak - Open source data platform for the Internet of Things. ThingSpeak Features
B4R - Development tool for native Arduino programs.
The IoT Guru - the IoT cloud backend company
PlatformIO - Next-generation IDE for IoT
dweet.io - Ridiculously simple data sharing for the Internet of Things.