StemMaster

StemMaster is a standalone tool for producers who want to mix and master already-separated stems. Its role-aware processing and section automation offer useful control, but the separate-app workflow and export-locked demo are real trade-offs.

Overview

StemMaster analyzes stems, mixes and masters them, and explains its processing decisions. It handles mixing rather than stem separation, so users need to export stems from a DAW and bring them into the app. That makes it a better fit for producers willing to work outside their DAW than for anyone seeking an integrated plugin workflow.

The maker says analysis, mixing and mastering run locally, and the built-in analysis engine works offline. The optional AI engine uses the user's API key with Anthropic, OpenAI, z.ai or compatible providers; it sends measurement summaries, not audio, to the selected provider. The app has no account, usage tracking, crash reporting or analytics SDK, and stores API keys in the operating system's credential store.

Key features

StemMaster balances, pans, equalizes and compresses stems according to measured roles. It can detect song sections and automate gain, pan, filters, reverb and stereo width by section. This goes beyond a static balance, though it depends on having prepared stems and continuing the work in a separate application.

A vocal rider and spectral unmasking—which can duck competing frequency ranges—offer more targeted control over vocal levels and masking. Reference matching uses a commercial track to guide tonal balance, width and dynamics while retaining the selected loudness target. The targets are Streaming −14, Club −9 and broadcast EBU R 128 −23 LUFS.

It loads WAV, AIFF, FLAC, MP3 and OGG stems and supports multiple export formats, including 24-bit audio and 32-bit float WAV. These format options suit varied stem sources and delivery needs, but StemMaster is standalone, not a VST plugin, and does not separate stems.

Pricing

The free demo is the full app, so users can assess its workflow before paying. It does not allow exporting, and mastered playback carries a periodic audio tag until licensed; that makes it useful for evaluating the tools, not for delivering finished work.

• Monthly subscription: $9.99 a month, billed monthly, cancellable any time. It covers up to 3 machines on Windows and macOS, with the license lasting through the paid period. This suits short projects or users who want to avoid a longer commitment.
• Annual subscription: $59 a year, billed once a year. It covers up to 3 machines on Windows and macOS, with the license lasting through the paid period. The lower annual cost than twelve monthly payments favors ongoing use, in exchange for paying a year at a time.
• Lifetime license: $99, paid once, billed one-time. It covers up to 3 machines on Windows and macOS and includes free 1.x updates. This is the fit for regular users who prefer a one-time purchase, though the included updates are limited to 1.x.

Platforms

StemMaster runs on 64-bit Windows 10 version 2004 or newer and Windows 11, or Apple Silicon Macs with macOS 15 or newer. Intel Macs are unsupported. The separate-app workflow means users must export stems from a DAW such as Ableton, FL Studio, Logic, Reaper or Cubase, then work on them in StemMaster. The maker says it answers questions publicly in its Gearspace thread.

Who it's for

StemMaster is a good match for producers who already have stems, want automated role-aware mixing and section changes, and value local processing. Reference matching and loudness targets also suit users working toward a particular tonal direction or delivery level. It is a poor fit for users who need stem separation, DAW-integrated plugins, Intel Mac support, or unrestricted exports during a free evaluation.

Pros and cons

• Pros: Role-based balancing plus section automation gives producers more than a one-pass static mix.
• Pros: Local processing and offline built-in analysis keep audio on the device; optional AI sends measurement summaries rather than audio.
• Pros: Reference guidance, named loudness targets and 24-bit and 32-bit float WAV export address common mix and delivery choices.
• Cons: No stem separation means users must bring prepared stems from elsewhere.
• Cons: No plugin support requires switching out of the DAW for mixing.
• Cons: The demo's export lock and periodic playback tag limit its usefulness for completing deliverables before purchase.
• Cons: Intel Macs cannot run it, and supported Apple Silicon Macs require macOS 15 or newer.

Alternatives

Browse AI Audio Mixing Software for more options in the category.

• StemDesk is worth considering if a free plan with stem separation, analysis, mix targets and local AI matters more than StemMaster's described section automation and reference matching; its free plan also includes compressor, gate and limiter plugins and WAV, MP3, FLAC and AAC export.
• Box may suit Mac users who want free session scanning, basic mix analysis and a stereo field view.
• NeuroMix AI is a web-based free option for occasional use, capped at 5 mixing sessions and 5 downloads per month, with uploads up to 10 MB and mixed WAV retention for 7 days.
• TonalBrain offers a different paid model: its $9, paid once Starter purchase includes 50 non-expiring credits, one per analysis run, with up to 24 tracks per run.
• Cryo Mix is a web-based paid alternative with a free trial.
• EZmix 3 is a paid macOS and Windows alternative with a free trial.
• FUSER is a paid alternative with a free trial for macOS and Windows hosts that support its listed AU, VST 3 or AAX formats.
• Waves Curves AQ is a paid macOS and Windows option with a free trial, included in Waves Ultimate subscriptions.

Verdict

Choose StemMaster if you have prepared stems, want role-aware mixing and section automation, and prefer local processing in a standalone app. Its strongest case is the combination of stem-level controls, reference guidance and local analysis; look elsewhere if stem separation, plugin integration, Intel Mac support or export-capable free use is essential.