MP3 MIME Type

About MP3 audio files

The registered type is audio/mpeg; audio/mp3 is a widespread mistake that browsers tolerate. For seeking in <audio> to work, the server must support range requests (Accept-Ranges: bytes and 206 responses).

Other types seen for these files: audio/mp3 , audio/mpeg3 . Accept them when reading uploads, but send audio/mpeg yourself.

File signature

MP3 files start with 49 44 33 ("ID3" tag), or FF FB / FF F3 / FF F2 (frame sync) without tags. The extension and the type a browser reports for an upload both come from the file name, so check these bytes on the server before trusting a file.

Serve .mp3 with the right Content-Type

Content-Type: audio/mpeg

audio/mpeg mp3;

AddType audio/mpeg .mp3

@mp3 path *.mp3
header @mp3 Content-Type "audio/mpeg"

curl -sI https://example.com/file.mp3 | grep -i '^content-type'
# Content-Type: audio/mpeg

Set the type in code

res.set('Content-Type', 'audio/mpeg');
// Or make the browser download it:
res.attachment('file.mp3');

import mimetypes

mimetypes.add_type('audio/mpeg', '.mp3')  # if your system doesn't know it
mimetypes.guess_type('file.mp3')[0]  # 'audio/mpeg'

mime.AddExtensionType(".mp3", "audio/mpeg")
w.Header().Set("Content-Type", "audio/mpeg")

Accept .mp3 uploads

<input type="file" accept=".mp3,audio/mpeg">

The accept attribute only filters the file picker; users can still choose another file. Listing the extension as well as the type matters, because operating systems don’t always report the type you expect.

Related types

• .m4a (audio/mp4): M4A audio
• .ogg (audio/ogg): Ogg audio
• .wav (audio/wav): WAV audio
• .aac (audio/aac): AAC audio

More audio

.flac . Look up any extension or type with the MIME type lookup.

Sources

• IANA registration: audio/mpeg
• MDN: Common media types

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Frequently asked questions