Audio Metadata Viewer

How to use the audio metadata viewer

1. Choose an MP3 file.
2. Read the tags below.
3. Nothing is uploaded or changed.

About this tool

Reads the tags embedded in an MP3. Both tag formats are supported: ID3v2, which sits at the start of the file and holds arbitrary named frames, and the older ID3v1, which occupies the final 128 bytes in fixed-width fields and truncates anything longer than thirty characters.

One detail is worth explaining because it is the classic bug in tag readers. ID3v2 stores its sizes as synchsafe integers — seven bits per byte, with the top bit always zero — so that a size can never contain a byte sequence resembling an MPEG frame header, which would confuse a decoder scanning for audio. Reading those as ordinary big-endian integers gives a value about 14% too large, and the result is garbled tags rather than an obvious failure. This decodes them correctly.

Text encoding is handled too. ID3v2 frames begin with an encoding byte specifying Latin-1, UTF-16 or UTF-8, and ignoring it turns non-English titles into mojibake.

Only the first 256 KB of the file is read to find the tags, plus the final 128 bytes. Reading a 200 MB file in its entirety to display a title would be slow and pointless.

Other formats use other schemes — Vorbis comments in OGG and FLAC, MP4 atoms in M4A — which this does not read, and it says so rather than reporting an untagged file.

Common uses

• Checking what metadata a file carries before sharing it.
• Finding the real artist or album of a badly named file.
• Confirming tags survived a conversion.

Frequently asked questions

Why are no tags found in my file?

It may genuinely have none, or it may use a format this does not read — Vorbis comments in OGG and FLAC, or MP4 atoms in M4A.

What is the difference between ID3v1 and ID3v2?

ID3v1 is 128 bytes at the end of the file with fixed-width fields that truncate at thirty characters. ID3v2 sits at the start, holds named frames of any length, and supports Unicode.

Is my file uploaded?

No. Only the first 256 KB and the last 128 bytes are read, on your device, which is all the tags occupy.