Equalizer APO
FreeA free, open source system-wide parametric equalizer for Windows that works as an audio processing object.
About Equalizer APO
Equalizer APO is a parametric and graphic equalizer for Windows that applies to the whole system rather than to a single player. It installs as an audio processing object in the Windows audio stack, so its filters affect any application that outputs sound through the chosen device.
Settings are stored in plain text configuration files, and the program supports an unlimited number of filters, several channel routing options and low latency processing. A configuration editor is included for those who prefer a visual approach, and the popular Peace interface is often installed on top for a friendlier front end. It is commonly used for headphone correction, room correction and general tone adjustment.
It suits audiophiles and tinkerers comfortable with an installer that asks you to pick the playback devices to modify. It is free and open source, with nothing to buy. Because it modifies the audio chain, an incorrect configuration can cause distortion, so keep a safe preamp setting when you try new filters.
Lower the preamp when boosting frequencies to avoid clipping. Many users add the separate Peace interface for easier editing.
Frequently asked
Is Equalizer APO free?
Yes. It is free and open source software.
Does it need an account?
No. It is a local installer with no sign-in.
Which platforms does it run on?
Windows only.
Where does the download link go?
Directly to sourceforge.net/projects/equalizerapo or the official app store for your platform. PlanetSofts never rehosts installers or adds wrappers, and these links were last verified Oct 6, 2026.