They were created by Frank D'Amato and it looks like he took his site down - I don't know why. You can still download the gauge ZIP file from djilogs.com using the 'Download' button at http://www.djilogs.com/#/dashware
I also purchased $10 credit with djilogs.com to convert the .dat files from my Phantom 3 Advanced to csv files for upload to AirData (previously known as HealthyDrones). This is because the Ground Station Pro mission planning app that I'm using doesn't provide flight logs, and the default DJI GO app flight log stops as soon as you switch to Ground Station Pro.
Unfortunately, the csv output from djilogs.com doesn't have key information that AirData needs to read the log (including a timestamp on each row of data). Djilogs.com therefore doesn't provide a useful output for me. Can you please refund the $10 to my card?