Free Online Audio Compressor
A dynamics compressor with threshold, ratio, attack, release, knee and makeup gain, plus a live gain-reduction meter.
Source
Loops while you adjust. Match loudness sets the effect to the same average level as the original while previewing, so you judge the tone and not the volume. It does not change the export.
Compressor
Drag a knob up or down, or focus it and use the arrow keys. Double-click or press Delete to reset one knob.
Meters
The safety limiter only protects the preview. The export is turned down as a whole if needed, so peaks stay under -1 dBTP.
Export
How to use the compressor
How to use it
The compressor turns down audio that rises above the threshold. Ratio sets how much: at 4:1, a signal 8 dB over the threshold comes out 2 dB over. Attack is how fast it reacts, release is how fast it lets go.
Watch the gain reduction meter while the file plays. Makeup gain brings the level back up afterwards.
Sensible starting settings
- Vocal: ratio 3:1, attack 5 to 10 ms, release 100 to 150 ms, threshold set for 3 to 6 dB of reduction.
- Full mix glue: ratio 2:1, attack 20 to 30 ms, release 150 to 300 ms, 1 to 2 dB of reduction.
- Drums with more punch: ratio 4:1 and a slower attack of 20 to 40 ms so the hit gets through.
Compare fairly
Makeup gain makes compression sound better just by being louder. Turn on Match loudness, then use bypass to hear only the change in dynamics.
Runs in your browser and exports a 24-bit WAV.
How it works.
- 1
Drop in a file
MP3, WAV, FLAC or M4A. It is decoded on your device.
- 2
Adjust while it plays
Turn the controls and hear the change live. Use bypass and loudness match to compare fairly.
- 3
Save a 24-bit WAV
Render the full file and download it with your plan access. Your original is unchanged.
Questions.
What compressor does this use?
The browser's built-in DynamicsCompressorNode, followed by a makeup gain stage. Both channels are compressed together.
Why does the meter not match my settings exactly?
The browser compressor has a small built-in look-ahead and its own knee curve. Treat the meter as a guide and trust your ears.
Can I use it as a limiter?
You can get close with a high ratio, fast attack and no knee, but it is not a true-peak limiter. The export is still kept under -1 dBTP by turning it down if needed.
Does it work on mono files?
Yes. Mono files are processed as two identical channels and saved as a stereo WAV.
Is my audio uploaded?
No. The file is decoded and processed in your browser with the Web Audio API. Nothing is sent to a server.
Can the export clip?
No. After rendering, the tool estimates the true peak between samples. If it would go above -1 dBTP, the whole file is turned down by the amount needed, and that amount is shown.