Professional grade audio analysis that runs entirely in your browser. No uploads, no accounts, no server. Your audio never leaves your device.

Try it live on tonalux.org

Drop any audio file and get instant measurements:

• LUFS Metering — Integrated, short-term, momentary loudness and LRA (EBU R128 / ITU-R BS.1770)
• True Peak — Intersample peak detection via 4x Catmull-Rom interpolation (dBTP)
• BPM Detection — Onset envelope analysis with autocorrelation
• Key Detection — Chromagram + Krumhansl-Kessler profiling (major and minor)
• Stereo Analysis — Width, phase correlation, and real-time goniometer
• Frequency Spectrum — 256-band log-spaced FFT with real-time overlay during playback
• Streaming Targets — Loudness comparison for Spotify, Apple Music, YouTube, Tidal, Amazon, Deezer
• Audio Playback — Click-to-seek waveform, spacebar play/pause

All DSP runs in a Web Worker off the main thread. Optional enhanced BPM/key detection via Essentia.js (loaded from CDN, graceful fallback).

git clone https://github.com/Exenye/tonalux-analyzer.git
cd tonalux-analyzer
python3 -m http.server 8080

Open http://localhost:8080. Any static HTTP server works (Python, Node, VS Code Live Server, etc.).

Supports MP3, WAV, FLAC, AAC, and OGG.

The signal processing pipeline implements broadcast standard loudness measurement:

1. K-Weighting — Two-stage biquad filter (high-shelf at 1681 Hz + high-pass at 38 Hz) per ITU-R BS.1770
2. Gated LUFS — 400ms blocks with absolute gate (-70 LKFS) and relative gate (-10 LU below ungated mean)
3. FFT — Cooley-Tukey radix-2 in-place, 8192-point for 5.9 Hz/bin resolution at 48kHz
4. True Peak — 4x oversampled Catmull-Rom interpolation to catch intersample peaks
5. Key Detection — Chromagram extracted from FFT bins mapped to pitch classes, correlated against Krumhansl-Kessler major/minor profiles via Pearson correlation

index.html          — HTML markup (121 lines)
css/analyzer.css    — Styles, dark theme, responsive (250 lines)
js/analyzer.js      — App logic, playback, canvas rendering (776 lines)
js/worker.js        — DSP Web Worker: FFT, LUFS, peaks, BPM, key (443 lines)

No build step. No bundler. No dependencies.

Chrome/Edge 66+ · Firefox 76+ · Safari 14.1+

This analyzer is part of Tonalux, a platform for audio professionals. Check out the other tools at tonalux.org.

MIT — see LICENSE.