RIOT powers the Internet of Things like Linux powers the Internet. RIOT is a free, open source operating system developed by a grassroots community gathering companies, academia, and hobbyists, distributed all around the world.
RIOT supports most low-power IoT devices, microcontroller architectures (32-bit, 16-bit, 8-bit), and external devices. RIOT aims to implement all relevant open standards supporting an Internet of Things that is connected, secure, durable & privacy-friendly.
Features
  • Standard programming in C, C++, or Rust
  •  Standard tools: gcc, gdb, valgrind
  •  Zero learning curve for embedded programming
  •  Code mostly without hardware dependence
  •  Benefit from POSIX APIs
  •  Develop under Linux, Mac OS, or Windows
  •  Use the native port, deploy on embedded device when running
  •  6LoWPAN, IPv6, RPL, UDP, TCP, QUIC
  •  MQTT-SN, CoAP, and CBOR
  •  BLE, LoRaWAN, 802.15.4, WLAN, CAN
  •  LwM2M client integration

 

You can download riot-os here