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Release Readiness Check
Before you send it to a distributor, find out what a distributor would find. Loudness and true peak against every major platform, plus clipping, mono compatibility, DC offset, dead air at the edges and the file format itself — all measured on your device. Nothing is uploaded, nothing to sign up for.
What this checks, and why
- Loudness per platform. Every service normalises to its own reference level. Anything above it is turned down on playback, so extra loudness costs dynamics and buys nothing.
- True peak and clipping. Over 0 dBTP, lossy encoding distorts audibly — and flat-topped runs of samples mean a limiter was pushed past the point where it can be undone.
- Mono compatibility. Clubs, phones and radio sum to mono. Out-of-phase content cancels there and takes the bass with it, and headphones will never show you.
- DC offset, dead air and file format. The small things distributors reject for, and the one mistake — mastering from an MP3 — that cannot be repaired later.
Frequently asked questions
Is my audio uploaded anywhere?
No — the file is decoded and analysed entirely in your browser with the Web Audio API. Nothing is sent to a server, and no account is needed.
What does mono compatibility mean?
Club systems, phone speakers, most Bluetooth speakers and radio sum the left and right channels together. If parts of your mix are out of phase, those parts cancel when summed and disappear — most often the bass. It is invisible on headphones, which is exactly why it survives all the way to release.
Why does true peak matter if my peak meter says 0?
A sample peak meter reads the samples. When a lossy encoder reconstructs the waveform between those samples it can overshoot them, so a file reading exactly 0 dBFS can distort after encoding. The −1 dBTP ceiling exists to leave room for that overshoot.
Should I master to −14 LUFS for Spotify?
Roughly, yes. Spotify normalises to about −14 LUFS, so anything louder is simply turned down — the extra loudness costs you dynamics for nothing. Master for the song rather than the number, but there is no advantage in sitting far above it.
Can I check an MP3?
You can, and the check will tell you it is lossy. The measurements are accurate for that file, but a master built from an MP3 permanently bakes in whatever the encoder discarded. Export a WAV or FLAC from your DAW and check that instead.