Two very different “faster”s
Keep pitch is what podcast apps do: the recording gets shorter but voices sound like themselves — right for lectures at 1.5×, interviews at 2×, or slowing to 0.75× while transcribing. Shift pitch is the physical effect of playing tape faster or slower: speed and pitch move together, which is the chipmunk sound at 2× and the deep slowed aesthetic at 0.5× — an effect people genuinely want for edits and memes.
Processing runs on FFmpeg in your browser — nothing uploads. Cut the interesting part first with the MP3 Cutter so you process seconds, not hours.