OBRA Audio Mastering (beta)
Professional audio mastering in your browser
Drop audio file here or
MP3, WAV, FLAC, AAC, M4AQuick Fix
Stereo
Polish
Output
Loudness
EQ
Free Online Audio Mastering
OBRA Audio Mastering is a free, browser-based mastering tool built for musicians, producers, and audio engineers. No downloads, no plugins, no subscription required. Drop your track, shape your sound, and export a release-ready WAV — all from your browser.
The mastering chain includes a professional-grade 5-band parametric EQ (80Hz, 250Hz, 1kHz, 4kHz, 12kHz), glue compression for mix cohesion, a true peak limiter with adjustable ceiling, M/S stereo width processing, and LUFS-targeted loudness normalization — the same tools used in professional mastering studios.
Quick-fix controls like de-harsh, clean low end, add air, and tape warmth let you polish your master in seconds. EQ presets for vocals, bass-heavy tracks, bright mixes, and warm masters give you a starting point, while the faders give you full manual control.
Export in WAV format at 44.1kHz or 48kHz, 16-bit or 24-bit — ready for Spotify, Apple Music, DistroKid, TuneCore, CD Baby, or any distributor. Your audio is processed entirely in your browser using the Web Audio API. Nothing is uploaded to any server.
OBRA Audio Mastering is currently in open beta. Using the mastering tool is completely free. To export your mastered file, simply sign in to your free OBRA account.
What you get
- 5-band parametric EQ with presets
- Glue compression & true peak limiting
- M/S stereo width control (0-200%)
- LUFS loudness normalization (-16 to -6)
- De-harsh, add air, tape warmth, add punch
- Real-time level meters with peak hold
- Waveform visualization
- Lossless WAV export (16/24-bit, 44.1/48kHz)
Who it's for
- Bedroom producers finishing their first track
- Rappers and singers mastering demos
- Podcasters and content creators
- Musicians who can't afford mastering engineers
- Audio engineers doing quick reference masters
- Anyone who needs a master — fast and free
Frequently asked questions
Is it really free?
Yes. The mastering tool is 100% free to use. You only need a free OBRA account to export your mastered WAV file.
Is my audio uploaded to a server?
No. All processing happens locally in your browser using the Web Audio API. Your files never leave your computer.
What formats can I import?
MP3, WAV, FLAC, AAC, and M4A. The browser decodes your file natively — no conversion needed.
What's the export format?
Lossless WAV at your choice of 44.1kHz or 48kHz, 16-bit or 24-bit. Ready for any distributor or streaming platform.
Can I use it on mobile?
The tool is optimized for desktop browsers. Mobile support is limited during the beta period.