OpenSprinkler is an open-source, web-based smart sprinkler controller for lawn and plant watering, drip irrigation, farm irrigation, hydroponics etc. The current version is OS 3.2, with built-in WiFi (based on ESP8266) and OLED display. You can choose between AC-powered, DC-powered, or Latch version. OpenSprinkler supports a variety of solenoid valves (24VAC, Latch, DC, motorized ball valve etc.) Take a look at FAQs for common questions, and Getting Started Guide for details of version 3.2. Among the new features, 3.2 supports built-in WiFi (ESP8266), Over-the-Air (OTA) firmware update, and 2 independent sensors.