This is an offline application for use with any flight simulator.
K-fs-sim-tool is a cross-platform aviation utility app designed to assist with:
Top of Descent Calculation
Required Descent Rate calculation
ETE & ETA Calculation
METAR & TAF Retrieval
Retrieving Airline callsign, IATA/ICAO codes etc
Where to fly (route) options
This app can be used with any flight simulator, if you are an msfs user, you can take advantage of the auto calculate feature for ETA and ETE provided the MSFS is connected to FSUIPC7 and SimConnect is working fine.