ESP8266 is Wi-Fi enabled system on chip module developed by Espressif. It is used for development of IoT embedded applications. Wifi module
esp-07 high resolution pinout and specs – Renzo Mischianti
NodeMCU v3 high resolution pinout and specs – Renzo Mischianti
ESP8266 Pinout Reference: Which GPIO pins should you use?
ESP12E WiFi Module : Datasheet, Working & Its Applications
NodeMCU ESP8266: Details and Pinout Arduino, Hobby electronics, Esp8266 projects
ESP8266 Pinout, Pin Configuration, Features, Example Circuit & Datasheet
NodeMCU ESP8266 Pinout, Specifications, Features & Datasheet
ESP32 WROOM 32D Pinout, Features, and specifications
Arduino UNO Rev 3: high-resolution pinout, datasheet, and specs – Renzo Mischianti