Inspect MP3 files — locally, in your browser
Find out what an .mp3 really contains before you use it: effective bitrate, duration, sample rate and channel count, read from the MPEG frame headers entirely on your device.
What this tool does
MP3 metadata tags can say anything — the frames tell the truth. This tool walks the actual MPEG frame structure in your browser and reports the real numbers, including VBR detection and an honest average-bitrate estimate.
Re-encoding MP3 files (compressing them to a lower bitrate) exists in the engine but is gated behind an encoder integration step; this page only claims the inspection path, which is fully implemented and tested.
How to inspect an MP3 file without uploading it
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Add the file. Drop your .mp3 into the home-page tool.
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Inspect. The MPEG frames are parsed locally — bitrate, duration, sample rate and channels.
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Act on the facts. Use the reported properties for your pipeline — with no upload having taken place.
Supported operations
This list is generated from CompressKit's capability registry — only implemented and tested operations appear here.
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Inspect file details
Walk the MPEG frames: bitrate, duration, sample rate, channels, VBR detection.
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Reduce file size
Supported in your browser — see the tool for details.
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Convert format
Supported in your browser — see the tool for details.
Frequently asked questions
- Does inspecting an MP3 upload it anywhere?
- No. The frames are parsed in your browser from the local file. Nothing leaves your device.
- What is VBR detection?
- Variable-bitrate MP3s change bitrate between frames. The inspector detects this and reports an average instead of pretending a single number applies.
- Can I compress MP3 files here?
- Yes — the file is decoded and re-encoded at a lower bitrate entirely in your browser. Re-encoding is lossy-to-lossy and warns you; ID3 tags are not preserved.
Ready to try it?
The MP3 audio inspector tool runs on this site with no upload step — your file is processed by your own browser and saved back to your device.
Open the MP3 audio inspector tool