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
PlatformIO - Next-generation IDE for IoT
The IoT Guru - the IoT cloud backend company
embedXcode - embedXcode is a template for Xcode.
dweet.io - Ridiculously simple data sharing for the Internet of Things.