True file type · audio
Is this really the format it claims?
A file name can say anything. Drop in a recording and this reads its actual signature bytes and
tells you the real format, and whether the extension is honest. A .mp3 that is
really a WAV, or a file that is not audio at all, shows up here.
Runs entirely in your browser. Your file is never uploaded or stored.
Why the extension is not the format
The name of a file, and the .mp3 or .wav on the end of it, is just a
label. Anyone can rename song.wav to song.mp3 and nothing about the
actual bytes changes. What really decides the format is a short signature at the very start of
the file: an MP3 carries an ID3 tag or an FF frame sync, a WAV starts
with RIFF, a FLAC with fLaC, an Ogg with OggS. This tool
reads those first bytes and reports what the file truly is, whatever it is called.
What a mismatch does and does not mean
A mismatch is a flag, not a conviction. Renaming happens for innocent reasons: an app exports
everything as .mp3, a converter leaves a stale extension, a download is misnamed. So
a WAV called .mp3 is usually just mislabelled. Where it matters is when a file is
presented as one thing and is quietly another, or when an extension has been changed to slip a
file past a check that only looks at the name. Read the result as a fact, then judge it in
context.
What it can miss
This reads the container format only. It can tell a FLAC from an MP3, but it cannot tell an
edited recording from an untouched one, and it does not judge audio quality. Note too that some
formats share a container: an .m4a and an .mp4 both start from the same
ISO structure and are told apart by a brand code a few bytes in, which this handles. For the
written tags and structural facts inside a recording, use the audio metadata reader when it
lands. Browse the full tool set for the rest.