| I built BPM Finder, a comprehensive audio analysis toolkit that provides three professional-grade tools: BPM detection, musical key identification, and tempo adjustment all running entirely in your browser. ## What makes it different: *Privacy-first approach*: Your audio files never leave your device. All processing happens client-side using Web Audio API, rubberband-wasm, and advanced algorithms. *Three powerful tools in one*:
- *BPM Finder*: Dual-algorithm analysis with 99.5% accuracy and confidence scoring
- *Key Finder*: Chroma analysis with correlation matrices for precise key detection
- *Tempo Change*: Adjust audio speed without pitch changes using professional rubberband algorithm *Multiple analysis modes*:
- Single file analysis with detailed results
- Batch processing (up to 50 files simultaneously)
- Real-time tap tempo for live BPM detection ## Technical highlights: - Built with Next.js 15, TypeScript, and Web Workers for intensive processing
- Supports MP3, WAV, FLAC, AAC, OGG, M4A (up to 50MB each)
- No registration required, completely free to use
- Export results to CSV or integrate with DAW/DJ software ## Real-world use cases: Professional DJs use it for beatmatching in live sets, music producers organize sample libraries by BPM, fitness instructors create tempo-matched workout playlists, and video editors sync background music to cuts. The project started when I needed reliable BPM detection for my own music production work but couldn't find tools that were both accurate and privacy-respecting. After months of research into audio analysis algorithms and Web Audio API optimization, I built this comprehensive solution. *Try it*: https://bpm-finder.net/ Would love feedback from the HN community, especially from fellow musicians, developers working with audio processing, or anyone who's tackled similar browser-based analysis challenges. *Tech stack*: Next.js, TypeScript, Web Audio API, rubberband-wasm, web-audio-beat-detector, Tailwind CSS |