Questions, answered plainly.

No. LevelAudio applies pure gain: the whole track moves up or down together, like turning the volume knob once and leaving it. No compression, no limiting, no pumping. The quiet intro and the loud chorus keep exactly the distance the mix gave them. If a track can't reach the target without its peaks clipping, it gets less gain and the app tells you, rather than squashing it.

Loudness isn't peak level: it's how loud a track feels. Two tracks with identical peaks can sit worlds apart, which is why matching by peak never quite works. LUFS measures felt loudness the way broadcasters and streaming platforms do (ITU-R BS.1770-4 / EBU R128), and LevelAudio shows you every track's reading before it changes anything. LUFS, explained.

−14 LUFS (the default) matches Spotify, YouTube and most streaming platforms and suits most music libraries. −16 LUFS is the usual recommendation for podcasts. −23 LUFS is the EBU R128 broadcast standard. Every target comes with a true-peak ceiling, so nothing clips.

MP3 volume can be changed by rewriting a gain field inside each frame instead of decoding and re-encoding the audio. Quality is untouched, tags and album art are kept byte for byte, and the change is exactly reversible. The trade-off: it works in 1.5 dB steps, so tracks land within ±0.75 dB of the target, which is inaudible in practice. Prefer the exact target? Switch MP3 handling to “re-encode for exact volume” in the app.

FLAC is compressed, so a gain change means decoding and re-encoding. That happens at the file's own bit depth and sample rate with FLAC's lossless compression: you get a normal FLAC of the same quality. It's still more invasive than the MP3 patch, which is why the app names the method used for every file. Which method each file gets.

No. Your browser opens the files, measures and adjusts them in memory, and writes the results back to your disk (or hands you a ZIP). There is no server side to this tool at all. How to check it yourself.

Any modern browser. Chrome and Edge on a computer can write the results straight back into the folder you picked (a new “normalized” subfolder, or in place if you ask). Firefox and Safari read folders fine and hand the results back as a ZIP download. On phones you can also share the results to Files or Drive.

By default your originals aren't touched: the results go to a new “normalized” folder. If you choose to replace the originals, keep backups, because there is no undo button. MP3s only have their gain fields changed, so their audio data is never rewritten; WAV and FLAC files are rewritten.

Yes. Your machine does the work, so each user costs us almost nothing. No account, no limits on the number of files. If LevelAudio saved your library an afternoon, there's a pay-what-you-want tip jar.