Speed a track up and raise its pitch together, right in your browser. That's the real nightcore effect: speed and pitch are locked, not adjusted independently.
It plays the track back faster, which raises the pitch as a side effect, exactly like speeding up a record. Speed and pitch move together here, so the result is the classic nightcore sound rather than an independent pitch shift.
Yes. A higher intensity plays more of the track per second, so a 1.3x edit finishes about 23% sooner than the original.
No. Decoding, processing, and encoding all happen in your browser with the Web Audio API. The file never leaves your device.