HLS (M3U8) Stream Tester: Master and Media Playlist Analysis

Why does an HLS stream stutter, which qualities does it offer, is its playlist in the right format? The tool downloads the M3U8 playlist for you, parses it and reports at master-playlist and media-playlist level: quality variants, resolution, bitrate, codecs, audio and subtitle tracks, segment count and durations, live or on-demand, encryption and problems found.