CapoThe mixing desk hiding in your browser tab.
One click changes the pitch, key, speed and volume of whatever’s playing — transpose a song to your range, slow a part down to learn it, or speed up a lecture. Processed on your device.
Four knobs. Every sound on the web.
Capo splices a real audio engine into the page and gives you direct control — no downloads, no re-encoding, no waiting.
Play it in any key you like.
Transpose a whole performance up or down by twelve semitones, in single steps — capo a song to sing along, or drop it to match the instrument in your hands. No warble, no chipmunk.
−12 … 0 … +12 semitones · 1-step resolution
Slow the hard part to a crawl.
From a quarter-speed practice tempo up to triple-time, the pitch stays exactly where you put it. Learn a lick by ear, or get through a lecture in half the time.
0.25× … 3× · 0.05× increments
Lock onto a phrase. Make it loud.
Set an A–B loop on the tricky four bars and let them repeat while you work them out. And when a video is mixed too quiet, push it well past the browser’s 100% ceiling — up to 300%.
A–B looping · volume up to 300%
Your listening never leaves your laptop.
Capo processes audio right inside the page. There’s no server in the loop, no account to create, and no record of what you play. The only thing it ever stores is your settings — locally.
Anyone who needs the sound a little different.
Musicians
Transpose to your key and slow passages down to learn them by ear.
Language learners
Slow a podcast to catch every word, or shift a voice to a register you parse.
Accessibility
Boost quiet videos past 100% and tame harsh, piercing frequencies.
Focus & study
Speed up lectures and talks, with your pace saved per page.
Three clicks from install to in-tune.
Add it to your browser
One install from the Chrome Web Store or Firefox Add-ons. No account, no setup.
Open it on any tab
Hit the toolbar icon while something’s playing — the page tunes to your controls instantly.
Retune, and it remembers
Pitch, speed and volume save per URL and come back exactly the same next visit.
Good to know.
Does Capo work on YouTube and Spotify?
Is my audio sent anywhere?
Will shifting the pitch make it sound like a chipmunk?
Does it remember my settings?
Is it free?
Guides for listening closely.
Why Slowing Audio Doesn't Have to Sound Like a Chipmunk
The tape effect, varispeed, formants and time-stretching — why modern speed control keeps the pitch natural, explained simply.
How to Learn a Song by Ear (Slow It Down, Loop It, Transpose It)
Slow the hard parts to a crawl, loop them until they stick, and transpose to a comfortable key — the complete by-ear method.
How to Change Pitch on Spotify, SoundCloud & Bandcamp
The Spotify Web Player, SoundCloud and Bandcamp don't ship pitch controls — Capo adds them to all three.