About MasterCheck

MasterCheck is a free, professional-grade audio mastering analysis tool built for modern music creators. Whether you're a bedroom producer, a professional mixing engineer, or a content creator, we provide the tools you need to ensure your audio meets the loudness standards of every major streaming platform.

Our Mission

We believe professional audio analysis should be accessible to everyone. That's why MasterCheck runs entirely in your browser — no server uploads, no account required, no compromises on privacy. Your audio files never leave your device.

Technology

MasterCheck is built with cutting-edge web technologies including the Web Audio API for real-time signal analysis and ffmpeg.wasm for browser-native audio conversion. Our LUFS measurements follow the ITU-R BS.1770-4 standard, the same specification used by professional mastering engineers and broadcast facilities worldwide.

Privacy First

We take your privacy seriously. All audio processing happens locally in your browser. We do not collect, store, or transmit your audio files in any way. The only data we store is a daily usage counter in your browser's local storage — and that never leaves your device either.

For Music Producers

We built MasterCheck because we understand the frustration of uploading a carefully mastered track to Spotify and having it turned down — or worse, clipping after encoding. With MasterCheck, you can verify your master meets the target before you upload, saving time and ensuring your music sounds exactly as intended on every platform.

Contact & Feedback

We're always looking to improve. If you have feature requests, bug reports, or just want to say hello, reach out via our contact page.