Grade Adjusted Distance
This Windows program will analyze a GPX file and use the formula for Grade Adjusted Pace (GAP) to estimate the Grade Adjusted Distance (GAD). GAD is an estimate of how far you would run on the flat for a given inclined distance to have a similar effort.
To use the program, download the zip file, extract, check for viruses, run the exe file. Note that you should get a warning from Windows that you are trying to run an untrusted program. You will need to tell Windows to run the program anyway. The program runs on Windows and requires .NET 7.0.