Audjust takes a song and builds a version that repeats without an audible break. You mark roughly where the loop should start and end, and it finds the cleanest spot to join the end back to the start so it plays over and over with no click or jump.
Here is the workflow. Upload an MP3 or WAV, and wait a few seconds for it to analyze. Drag your start and end points to roughly where you want them; Audjust snaps each one to the nearest clean cut. Play the loop back to hear the repeat, then export the finished file. You can also pull a short section out as a sample instead of keeping the whole track.
This helps when you need a piece of music to run longer than it was recorded: a backing track for a stream, music under a video that outlasts its soundtrack, a focus or study track you want on repeat, or a loop dropped into a game.
One tip for clean results: a loop sounds best when both ends land at the same point in the rhythm, so try to start and end on a downbeat and cover a whole number of bars. That usually beats trimming by ear.
No install, no signup, no cost. It runs in your browser, so you can upload a song, make a loop, and download it in one sitting.