Yes. Infinite DDR (ddrinfinity.com) takes any YouTube song by name or link, pulls the audio, detects the beat and generates a DDR-style step chart at five difficulties, playable in the browser on a computer or phone. No download, no account.

An onset detector finds drum and vocal hits, a tempo tracker locks the beat grid, and a two-foot stepping model places arrows on the song's groove: quarter notes at Beginner, 8ths at Difficult, 16th bursts, crossovers and jumps at Expert and Challenge. Charts are generated, not hand-stepped, and the same for every player so scores compare. A second generator trained on open StepMania simfile packs (Fraxtil, Club Fantastic) can be toggled.

Beginner, Basic, Difficult, Expert and Challenge, rated in feet like the arcade (roughly 2 to 14) from notes per second, jumps and freezes.

DDR timing windows: Marvelous within 22.5 ms, Perfect 45 ms, Great 90 ms, Good 135 ms, Boo 180 ms, otherwise Miss. Jumps are judged as one row. Freeze arrows give O.K. or N.G. The money score is out of 1,000,000 and grades run AAA, AA+, AA, AA-, A+, A, A-, B, C, D, with E on a fail.

Arrow keys or D F J K on a keyboard. On phones the four panels are a tappable DDR cross (or one row), with multi-touch for jumps. A sync calibration tool measures your audio latency. USB dance pad support is planned.

Yes, in the browser, and it can be added to the home screen as an app that launches full screen.

Each song has a world board per difficulty, there is a global board of top plays, and the home page shows what people around the world are playing. Any song someone has played starts instantly for everyone.

StepMania plays hand-stepped simfiles you install. Infinite DDR charts any song on the fly with no files, so it is a jukebox you can dance to rather than a simulator; its charts are not yet the quality of a good hand-stepped pack.

No. It is free, with no ads and no account.