Transpose any YouTube video into your key. Slow it down to learn a solo. Loop four bars until they click. Tonika is a musician's toolbox for YouTube — pitch shift, speed control, and A-B loops, all running locally in your browser. ━━━ FEATURES ━━━ - Pitch shift ±12 semitones — transpose any video to any key - Fine tune ±100 cents — handle off-pitch recordings, alternate tunings, A=432 Hz reference - Speed 25% to 400% — slow down to transcribe, speed up to skim - Decoupled pitch and speed — change tempo without the chipmunk effect (powered by SignalSmith Stretch phase-vocoder WASM) - A-B loop with named regions — set precise markers, name your loops, practice sections on repeat - Per-song memory — come back to a video and Tonika restores your last pitch, speed, and loop automatically - Keyboard shortcuts — Alt + Shift + arrows for hands-on-instrument control - Recent songs list — jump back to anything you adjusted in the last 50 videos - Light and dark theme — follows your system or pick manually - Works on youtube.com and youtube-nocookie.com (embedded players) ━━━ WHO IT'S FOR ━━━ - Singers matching a song to your vocal range - Guitarists practicing with backing tracks in drop D, half-step down, or any tuning - Piano students slowing down a Chopin interpretation to learn the left hand - Drummers looping a fill to nail the sticking - Jazz musicians transcribing solos at half speed without the pitch dropping an octave - Teachers making YouTube lessons accessible at slower tempos - Producers referencing songs at different tempos without re-encoding ━━━ HOW IT WORKS ━━━ Click the Tonika icon while a YouTube video is playing. Drag the Transpose slider to change key. Drag Speed to slow it down. Flip on A-B Loop to practice a section on repeat. Everything responds live — no re-buffering, no re-encoding, no uploads. Tonika uses the Web Audio API + SignalSmith Stretch (an open-source, MIT-licensed phase-vocoder compiled to WebAssembly) to shift pitch without affecting speed and vice versa. The video stays frame-synced with the audio at all times. ━━━ KEYBOARD SHORTCUTS ━━━ Default shortcuts (customize in chrome://extensions/shortcuts): - Alt + Shift + Up / Down — pitch up / down 1 semitone - Alt + Shift + Right / Left — speed up / down 5% - A-B loop toggle — assign your own key ━━━ PRIVACY ━━━ Tonika runs entirely in your browser. No account, no sign-in, no analytics, no tracking, no telemetry, no network calls to any Sopivasti server. All audio processing happens locally in the tab. Your preferences and recent-songs history are stored in Chrome's built-in sync storage (syncs between devices signed into the same Chrome profile — never sent to us). Full privacy policy: https://sopivasti.com/privacy ━━━ WHAT'S NOT SUPPORTED ━━━ - Spotify Web Player — streams encrypted audio via Widevine EME with no DOM media element, so browser extensions cannot attach to its audio graph - Apple Music Web, Deezer, Tidal — same architecture, same limitation - SoundCloud, Bandcamp, Vimeo — planned for v0.2, based on request volume