- What it is: A free, browser-based 4-band audio equalizer.
- Cost: Free. No signup, no account, no ads.
- Privacy: Audio is processed entirely in your browser and is never uploaded to a server.
- Formats supported: MP3, WAV, M4A, OGG.
- EQ bands: 60Hz, 500Hz, 2.5kHz, 8kHz — each adjustable from -12dB to +12dB.
- Platform: Works in any modern desktop or mobile browser.
A free online equalizer for any audio file
QuadEqualizer is a free, browser-based audio equalizer for shaping the sound of any MP3, WAV, or M4A file. Drag four faders to boost or cut the low, low-mid, high-mid, and high frequency bands in real time, watch the live spectrum respond, and hear the change instantly — no app, no plugin, no account.
Unlike most online equalizer tools, nothing is uploaded to a server. QuadEqualizer uses your browser's built-in Web Audio API to decode and process the file on your own device, so your music never leaves your computer or phone. That makes it a fast, private way to boost bass, tame harsh vocals, brighten treble, or preview how a mix will sound with different EQ curves before committing to changes in a full DAW. New to EQ? Our resources and guides cover the basics.
Using the equalizer
- Load a track. Choose a file from your device or drag an MP3, WAV, or M4A into the drop zone. The file stays local — it's never uploaded anywhere.
- Adjust the four bands. Drag the Low (60Hz), Low-Mid (500Hz), High-Mid (2.5kHz), and High (8kHz) faders up to boost or down to cut, from -12dB to +12dB.
- Watch the spectrum. The built-in analyzer shows which frequencies are active in real time, color-coded to match each band.
- Try a preset. Jump-start your sound with Bass Boost, Vocal, Treble, or Smiley (V-curve), then fine-tune from there.
- Set the volume and play. Use the master knob to balance overall output, then hit play to hear your EQ applied live.
What's under the hood
Frequently asked questions
Q. Is QuadEqualizer really free?
Yes. It's completely free to use, with no account, subscription, or watermark on the audio.
Q. Do I need to install anything?
No. QuadEqualizer runs directly in your web browser. There's nothing to download or install, and it works on desktop and mobile.
Q. Is my audio file uploaded to a server?
No. Your file is decoded and processed locally in your browser using the Web Audio API. It's never uploaded, stored, or sent anywhere.
Q. What audio formats does it support?
Any format your browser can decode, including MP3, WAV, M4A, and OGG.
Q. Can I use it on my phone?
Yes. The interface is fully responsive and works on mobile browsers as well as desktop.
Q. Can I equalize Spotify or YouTube audio directly?
Not currently — QuadEqualizer works with local audio files (MP3, WAV, M4A, OGG) you choose or drop in, not streamed audio from other apps or sites.