Free Online Mastering, in Your Browser.
Real metering. True-peak safe.
A transparent mastering chain for Spotify, Apple Music, YouTube, club, broadcast and vinyl targets. Upload your mix, dial in a 9-stage chain you can actually hear, and export with real LUFS and true-peak metering — no card, no subscription.
Before and after, at matched loudness
Anything sounds better when it is louder. This demo plays both versions at the same measured loudness, so what you hear is tone and dynamics — not volume. The processing runs live in your browser through the exact chain the studio uses.
Mastering for every platform — Spotify, Apple Music, YouTube and more
Each platform normalises loudness differently. Quantara normalises toward the reference for your destination and holds a true-peak-safe ceiling — club, broadcast and vinyl targets included.
Genre presets: mastering tuned for 34+ styles
Pop, Hip-Hop, EDM, Metal, Jazz, Afrobeats, K-Pop, Cinematic and more — each preset is a genre-aware starting point. You dial in every stage from there; mastering always responds to the track in front of you, not just a label.
What a professional mastering chain gives you
Built by engineers, for producers.
9-Stage Mastering Chain
HPF, sub shelf, low-mid cleanup, presence, air EQ, true mid/side stereo width, glue compression, harmonic saturation, and a true-peak limiter. Every stage adjustable in real time, with A/B bypass.
all major Loudness Targets
Normalised references for Spotify, Apple Music, YouTube, Tidal, Amazon, Deezer and iTunes; loud creative presets for Club, Beatport and SoundCloud; plus specialised targets: EBU R128 broadcast and vinyl.
AI Stem Separation
Split any track into vocals, drums, bass and instruments. Six separation modes, from fast previews to studio-grade quality.
34+ Genre Starting Points
7 categories: Pop & Mainstream, Urban, Electronic, Rock & Metal, Latin & World, Acoustic & Classical, and Other. Each is a sensible starting point for the genre — then you adjust to the actual track.
Real-time Metering
Live spectrum, BS.1770 loudness (LUFS), true-peak detection, waveform with click-to-seek, and gain-reduction read straight from the compressor and limiter — not estimated.
Reference Matching
Upload any commercial track as a reference and match its tonal balance, dynamics and loudness. Available on Pro and above.
Cloud Library
All uploads and masters stored securely. Search, filter, tag, annotate with BPM and key. Download anytime from any device. Load directly into Studio.
Multi-Format Export
WAV 16-bit (CD quality), WAV 24-bit (studio), WAV 32-bit float (Label plan). True-peak limited at −1 dBTP. Saved automatically to your Cloud Library.
REST API Access
Label plan includes full API access with personal API keys. Automate your mastering pipeline, integrate with your DAW workflow or CI/CD system.
How online mastering works — three steps, full control
No plugin to install. Works entirely in your browser.
Upload your mix
Drag and drop any WAV, FLAC, MP3, M4A, AIFF or OGG file up to 500MB. Audio processing happens in your browser — your audio never leaves your machine unless you save it to your Cloud Library.
Choose your target & dial in your sound
Pick a loudness target and a genre starting point, then fine-tune all 9 stages in real time. A/B bypass lets you hear exactly what each move does.
Export, normalised and true-peak safe
Click Export. Quantara measures the integrated loudness (BS.1770), normalises toward your target, and applies a true-peak limiter at your ceiling (default −1 dBTP). Free accounts get 3 exports/month; Pro and above are unlimited.
Free mastering plans — start free, scale when you're ready
No hidden fees. Cancel anytime. Annual plans save 2 months.
Free plan with 3 exports/month, plus Pro, Studio and Label tiers.
Open Studio to see current plans →Transparent mastering you can hear and measure
No invented numbers, no fake quotes. Judge it the way an engineer would — with your ears and real meters.
Hear every decision
A fully adjustable 9-stage chain with instant A/B bypass. Try the Before / After demo above on your own track — it runs entirely in your browser, nothing uploaded.
Measured, not guessed
Loudness is metered to the BS.1770 standard, peaks are read as true-peak, and gain reduction comes straight from the compressor and limiter — not estimated from a spectrum.
Honest by design
Exports normalise toward each platform's loudness reference and hold a true-peak-safe ceiling, instead of crushing everything to a loudness-war number. For high-stakes releases, it complements critical listening rather than replacing your ears.