StemMaster

StemMaster is a standalone app for analyzing, mixing and mastering audio stems, best suited to producers who want role-aware processing and local audio handling. Its section automation and reference matching make it more than a basic stem balancer, but it requires a separate-app workflow and a paid license to export.

Overview

StemMaster analyzes stems, mixes and masters them, and explains its processing decisions. It works with audio already separated into stems; it does not separate stems itself. Because it is standalone rather than a DAW plugin, users need to export stems from a DAW and continue the work in StemMaster. That is a sensible trade-off for producers comfortable moving between apps, but a poor fit for anyone who wants processing directly inside a DAW session.

The maker says analysis, mixing and mastering run locally and audio is never uploaded. Its built-in analysis engine works offline. The optional AI engine uses the user's API key with Anthropic, OpenAI, z.ai or compatible providers, sending measurement summaries rather than audio. The app has no account, usage tracking, crash reporting or analytics SDK, and stores API keys in the operating system credential store.

Key features

StemMaster balances, pans, equalizes and compresses stems according to their measured roles. It can also detect song sections and automate gain, pan, filters, reverb and stereo width by section. This gives producers a way to shape changes across a track rather than rely on one static balance. A vocal rider and spectral unmasking, which can duck competing frequency ranges, provide further control around vocals and masking.

Reference matching uses a commercial track to guide tonal balance, width and dynamics while retaining the selected loudness target. The available targets are Streaming −14, Club −9 and broadcast EBU R 128 −23 LUFS. StemMaster accepts WAV, AIFF, FLAC, MP3 and OGG stems, with multiple export formats including 24-bit audio and 32-bit float WAV.

The free demo includes the full app, but it cannot export, and mastered playback carries a periodic audio tag until licensed. It is useful for exploring the workflow, not for delivering a finished master.

Pricing

StemMaster has a free demo and three paid licenses. The demo lets users try the full app, but the export lock and playback tag make a paid license necessary for usable output.

• Monthly subscription: $9.99 a month, billed monthly; cancel any time. It covers Windows and macOS on up to 3 machines and lasts through the paid period. This suits occasional or short-term use without a larger upfront payment.
• Annual subscription: $59 a year, billed once a year. It includes the same platform coverage and up to 3 machines, with the license lasting through the paid period. It costs less than twelve monthly payments, but requires an annual commitment.
• Lifetime license: $99, paid once, billed one-time, for Windows and macOS on up to 3 machines, with free 1.x updates. It is the clearest fit for regular users who prefer to avoid recurring payments; the stated update entitlement is limited to 1.x.

Platforms

StemMaster runs on 64-bit Windows 10 version 2004 or newer and Windows 11, or on Apple Silicon Macs with macOS 15 or newer. Intel Macs are unsupported. Its standalone format means it does not require a plugin host, but producers must export and import stems between it and their DAW. The maker says it answers questions publicly in its Gearspace thread.

Who it's for

StemMaster suits producers who already have stems, want automated role-aware mixing and mastering controls, and prefer audio processing to stay local. It is less suitable for users who need stem separation, a DAW plugin, Intel Mac support, or a demo that can export finished audio.

Pros and cons

• Pros: Role-aware stem balancing, section-based automation, vocal tools and reference matching give producers several ways to shape a mix beyond static level adjustment.
• Pros: Local processing and offline built-in analysis keep audio on the user's machine; optional AI sends measurement summaries, not audio.
• Pros: Up to 3 machines are covered, and the lifetime license includes free 1.x updates.
• Cons: There is no DAW plugin or stem separation, so users must bring prepared stems into a separate app.
• Cons: The demo cannot export and adds a periodic audio tag to mastered playback, preventing a complete evaluation through deliverable files.
• Cons: Intel Macs are unsupported, and Apple Silicon users need macOS 15 or newer.

Alternatives

StemDesk is a better match for users looking for a free entry point with stem separation, analysis and mix targets, a local AI suite, and export; its free plan also includes Compressor, Gate and Limiter plugins.

Box is worth considering for Mac users who want session scanning, basic mix analysis and a stereo field view on a free plan, with a paid Pro option.

NeuroMix AI fits web users who want a free tier for occasional mixing, capped at 5 sessions and 5 downloads monthly, 10 MB uploads, and seven-day retention of mixed WAV files.

TonalBrain offers a lower-cost one-time Starter purchase at 9.00 USD for 50 credits, with credits that never expire; it suits users whose needs fit 1 credit per analysis run and up to 24 tracks per run.

Cryo Mix is a web-based alternative with a free trial.

EZmix 3 may suit users who prefer a DAW-hosted tool and can use its trial; the listed 69.00 EUR upgrade requires owning a previous EZmix version and eligibility is checked after login.

FUSER is another paid, trial-available option for users with a compatible 64-bit AU, VST 3 or AAX host on macOS or Windows; its listed one-time price is 59.00 GBP.

Browse the AI Audio Mixing Software category for more options.

Verdict

StemMaster is a strong choice for producers with prepared stems who want role-aware processing, section automation and reference matching without uploading audio. Its main advantage is the breadth of its standalone workflow; its main drawback is the need to leave the DAW, compounded by an export-locked demo and no stem separation. Choose it if those trade-offs fit your process, and look elsewhere if you need integrated plugin work or support for Intel Macs.