ESP8266

Unofficial SDK:     https://github.com/CHERTS/esp8266-devkit
– with forum at:  http://www.esp8266.com/viewtopic.php?f=9&t=820

ESP8266 Community Wiki:     http://www.esp8266.com/wiki/doku.php

NURDspace ESP8266:     https://nurdspace.nl/ESP8266

Firmware to enable Lua:     https://github.com/nodemcu/nodemcu-firmware

Lua IDE:     http://esp8266.ru/esplorer/

Comparison of different chip versions:
http://l0l.org.uk/2014/12/esp8266-modules-hardware-guide-gotta-catch-em-all/

Scargill’s Tech Blog:     http://tech.scargill.net/

 

MQTT

MQTT for the ESP8266:     https://github.com/tuanpmt/esp_mqtt
 – wiki and forum

mqtt-spy utility:     http://kamilfb.github.io/mqtt-spy/

HiveMQ blog series:     http://www.hivemq.com/mqtt-essentials-part-1-introducing-mqtt/

MQTT broker in the cloud (free):     http://www.cloudmqtt.com/plans.html