Make sure you use one of the supported versions of Arduino IDE and have ESP8266/ESP32 core installed. Download the tool archive from releases page. In your Arduino sketchbook directory, create tools directory if it doesn't exist yet. Unpack the tool into tools directory (the path will look like <home_dir>/Arduino/tools/EspExceptionDecoder/tool/EspExceptionDecoder.jar). Restart Arduino IDE.
Download the tool archive from releases page.