SirenMix — Free browser-based BPM changer & audio converter for DJs (no upload, runs locally)

Hey everyone,

I’ve been building a set of browser-based audio tools aimed at DJs. Everything runs locally in your browser using FFmpeg compiled to WebAssembly — your files never leave your device.

BPM Changer

  • Auto-detect BPM, change tempo with pitch preservation

  • Preview in real time before exporting

  • Useful for prepping edits before importing to your DJ software

Audio Converter

  • Convert between MP3, WAV, FLAC, AAC, OGG

  • Batch processing supported

  • Handy for quick format conversions when you need a compatibility copy for a USB or backup

Both tools are free, no account required to use them:
https://sirenmix.com/tools

I also started writing some practical guides (audio formats comparison, BPM ranges by genre, harmonic mixing reference) if anyone’s interested: https://sirenmix.com/blog

Would love to hear feedback from working DJs — what’s missing, what could be better, or if this is actually useful in your workflow.