Compare versions of the same audio stacked like a multitrack (before and after, your mixes, a reference) and switch between them without stopping playback: the next one comes in at the same instant, with an 8 ms fade, so there's no click. GAIN MATCH evens them by loudness, so you compare the sound, not the level.
Comparisons can also be shared with a link and played in any web browser.
It opens what TapeLeader's COMPARE · SYNCHEAD writes.
Requirements: Windows 10 or 11, 64-bit.