Getting Started with Capo: The Complete Guide

Capo is a free browser extension that gives you a small mixing desk for the whole web. It can change the pitch and key, the speed, the volume, and loop a section of any audio or video playing in your tab — all in real time, and all processed on your own device. This guide covers everything it does and how to use it.

Install the extension

Add Capo from the Chrome Web Store or Firefox Add-ons. It's one click, with no account and no setup. Once installed, click its toolbar icon on any tab that's playing audio or video, and the controls appear.

Change the pitch and key

The pitch dial moves the music up or down by up to twelve semitones in each direction, in single steps — a full octave either way. Crucially, it does this without changing the speed, so nothing turns into a chipmunk.

Singers use it to transpose a song into a comfortable key; guitarists use it to match a track tuned down a half step. For the full walkthrough, see how to change the pitch of any song.

Change the speed

The speed fader runs from 0.25× up to 3×, with the pitch held constant the whole way. Slow a solo to a crawl to learn it, or push a lecture to 2.5× to get through it — voices stay natural at both ends.

See slowing down YouTube and speeding up videos and podcasts for the details.

Loop a section (A–B)

Mark a start point (A) and an end point (B) and Capo repeats just that passage — perfect for drilling four hard bars or replaying a phrase in another language until it sticks.

Boost the volume

When a video is mixed too quietly, Capo can push its volume past the browser's 100% ceiling — up to 300% — so a faint clip becomes comfortably audible.

Your listening stays on your device

There's no server in the loop. Capo processes the page's audio right inside your browser, so nothing about what you play is ever uploaded, and it works fully offline. The only thing it stores is your settings — locally.

Ready to put it to work? A great first project is learning a song by ear.