This is board manager .json link for Arduino IDE.

ESP tutorials LINK

ESP32

ESP32 Github Arduino Core

Stable

https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json

or

https://dl.espressif.com/dl/package_esp32_index.json

Development

https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_dev_index.json

ESP8266

ESP8266 Github Arduino Core

https://arduino.esp8266.com/stable/package_esp8266com_index.json