Oscilloscope
Watch the raw waveform over time. Switch between Waveform and Lissajous (XY), tune the time and vertical scale, and let auto-trigger lock the trace to check phase and stereo image.
- Waveform
- Lissajous (XY)
SPV-2
Studio-grade meters, in your sidebar.
Five real-time meters for reading sound — waveform, spectrum, notes, BPM, and key — right in your browser's side panel.
Add to Chrome Free · Open source · No tracking
See it move.
Watch all five meters react to live sound.
SPV-2
Five meters
Each meter reads one dimension of sound — built to be read, not just admired.
Spectrum Analyzer
A 32-band logarithmic FFT lays out the whole spectrum from lows to highs. Peak-hold and frequency labels make it easy to spot a muddy low end or a harsh top.
- 32-band FFT
- Peak hold
Chromagram
Detects the pitch classes sounding right now — polyphonically — and maps them onto a piano keyboard. Note Flow scrolls the harmony past as a moving ribbon.
- Polyphonic
- Note Flow
BPM Detection
Picks up onsets with spectral flux and estimates tempo by autocorrelation. The track's BPM reads out live — a quick reference for beatmatching or transcribing.
- Spectral flux
Key Detection
Estimates the key from the chroma profile and shows it in DJ-friendly Camelot notation — so you can pick a harmonically matching next track in seconds.
- Camelot
Track Info
Title, channel, BPM, and key in one compact readout — the identity of whatever's playing, always next to the meters.
40+ themes
Ten built in — Default, Neon, Monochrome, Amber, Phosphor, Sakura and more — plus Strudel-derived variants for 40+ in total. Recolor the meters to match your mood or the lighting in the booth.
Tap a swatch to recolor the meters.
Pick a theme
10 built in + 41 from Strudel
Strudel auto-sync: when you're capturing strudel.cc, the meters automatically follow your editor's theme.
Where it works
Works out of the box across the major music and video services — and extends to anywhere you need.
| Service | URL pattern | Notes |
|---|---|---|
| YouTube | *://*.youtube.com/* | Includes music.youtube.com |
| SoundCloud | *://*.soundcloud.com/* | |
| Bandcamp | *://*.bandcamp.com/* | |
| Beatport | *://*.beatport.com/* | |
| Mixcloud | *://*.mixcloud.com/* | |
| Spotify | *://open.spotify.com/* | DRM streams may not be capturable |
| Apple Music | *://music.apple.com/* | DRM streams may not be capturable |
| Amazon Music | *://music.amazon.co.jp/* | Japan domain only (.co.jp) |
| Tidal | *://*.tidal.com/* | DRM streams may not be capturable |
| Strudel | *://strudel.cc/* | Theme auto-sync — meters follow your editor |
+ All websites — enable any site you like under Settings › Advanced.
Matching is by exact hostname or subdomain.
Note: DRM-protected streams (such as Spotify Premium, Apple Music subscriptions, or Tidal HiFi) may not be capturable — this is a browser-side limitation.
Zero interference
SPV-2 doesn't touch the page, doesn't track you, and doesn't send anything out. Audio is captured via Chrome's tabCapture API and processed entirely inside the extension.
-
No content scripts
Nothing is injected into the page's DOM. The site you're viewing stays exactly as it is.
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No tracking
No analytics, no telemetry, no ads. None of your listening is collected.
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Zero network
No outbound requests at all. Everything happens on your machine.
Manifest V3 · audio processed in an Offscreen Document · open source under the MIT license.
Three principles
- Zero Injection
Never touch the page — no content scripts, no DOM injection.
- Local by default
Everything runs locally — no servers, no telemetry.
- One panel, one job
All the meters live in one side panel — no tab-switching.
Release notes
Since launch, the meters, supported sites, themes, and languages have grown steadily.
- v1.3.1
Smoother low-end in the Spectrum view: the lowest bars no longer flatten out, now interpolated cleanly down to 20 Hz. Spanish localization added.
- v1.3.0
Japanese and German localization (both the extension UI and the Web Store listing).
- v1.2.0
Strudel integration. Added 41 Strudel-derived themes; on strudel.cc the meters auto-sync to your editor theme. New theme picker, too.
- v1.1.0
Multi-site support. Added 10+ sites beyond YouTube, an All-websites mode, a vertical scale for the Oscilloscope, and a confirmation step before the permissions dialog.
- v1.0.0
First release. Five meters (Oscilloscope, Spectrum, Chromagram, BPM, Key) plus Track Info, ten themes, and a customizable layout.
Start watching your sound.
Open the side panel and the song you're already playing comes alive on the meters.
Add to ChromeFree · MIT licensed · No tracking