Any development above low-level programming for hardware:
Development frameworks / SDK
Node.js IoT.js Device.js
Java and Eclipse IoT (Kura, SmartHome)
Particle DeviceHive openHAB
Communication Protocols
Wi-Fi USB Serial IPv6 cellular 2/3/4G
Bluetooth CoAP MQTT Z-Wave ZigBee
EIB XMPP AMQP HTTP/HTTPS Sigfox LoRaWAN
Hardware
Raspberry PI Arduino KNX Crestron
сonsumer smart home hubs (Samsung, Philips, D-Link, etc.)
industrial gateways (Intel, Cisco and Eurotech) ESP32 (by Espressif)