Audio Compressor
Reduce MP3, M4A, WAV, OGG, FLAC, or AAC file size locally with bitrate presets, optional sample-rate changes, and ZIP export for batches.
The three presets are really just three different target bitrates — lower bitrate means a smaller file at the cost of some audio fidelity, and the "right" one depends more on what the audio is than a fixed rule. Spoken-word content like a podcast episode holds up fine at a much lower bitrate than music does, since there's simply less going on in the frequency spectrum for compression to lose — it's worth trying the smallest preset first on voice content before assuming quality needs to be prioritized.