Not just another note sender

PostFader is a production layer for FL Studio—not only a way to send notes or change isolated controls. It gives your AI useful context from the project that is open now, plus tools to analyze exported audio, work with loaded plug-ins, compose musical parts, and carry separately requested supported changes back into the session.

Four ways to work with PostFader

🔎 Understand the project already open

“Show me every instrument that is not routed to the mixer.”

“Which effects are loaded on my lead vocal?”

“Where are my drums routed, and which mixer inserts are peaking too high?”

PostFader reads FL Studio's current project state: mixer inserts and sends, loaded mixer effects, Channel Rack generators, patterns, Playlist track state, transport, undo/redo history bounds, the current step grid, and exposed plug-in parameters. Your AI can answer from the actual session instead of relying on a project description pasted into chat.

🩺 Diagnose an exported mix and decide what to improve

“What are the three highest-impact problems in this bounce?”

“Compare this mix with my reference and explain the biggest differences.”

“Check these vocal and instrumental exports for likely masking.”

Mix Doctor turns an exported bounce into producer-readable technical findings about level, dynamics, tonal balance, stereo behavior, and export readiness. Reference analysis compares loudness and tonal balance across aligned audio. Masking analysis uses synchronized vocal and instrumental renders to report possible spectral-overlap regions.

During a chosen observation window, a peak watch samples the mixer inserts included in the watch and remembers the highest level it observed for each. Use those results to build a gain-staging plan from a playback section or full pass that fits the window rather than a single instant. These are sampled observations, so they do not prove that every transient was captured. Your AI can use other reported findings to create a separate, reviewable mix plan.

🎛️ Control the session and the plug-ins you already use

“Rename insert 4 to Lead Vocal, color it purple, pan it 10% left, and confirm the changes.”

“Mute the backing-vocal tracks and lower the send to the reverb bus.”

“Find the feedback parameter on the delay that is already loaded and reduce it.”

PostFader can control mixer volume, pan, mute, solo, arm, selection, stereo separation, sends, and routing. It can change tempo, playback, loop mode, recording state, and song position; organize channels, patterns, and Playlist tracks; and edit step sequences.

For loaded effects and Channel Rack generators, PostFader asks FL Studio which parameters the plug-in exposes. It can inspect names and values, search or scan large parameter surfaces within explicit limits, set a known value, target the number a plug-in displays, or choose an exact named option. Bundled profiles for selected FL Studio stock effects add known parameter roles for supported workflows without pretending every plug-in has the same controls.

For those selected profiles, your AI can turn supported goals such as “tame harshness,” “control dynamics,” “limit peaks,” “shorten the reverb,” or “create a rhythmic echo” into matching parameter roles. Intent resolution is read-only; choosing values and applying a change remain separate steps.

PostFader works with the chain already in the session. It does not currently insert, remove, or reorder plug-ins, and FL Studio does not expose reliable effect-slot bypass or wet/dry control here.

🎹 Compose, transform, and organize musical ideas

“Create an eight-bar D Dorian melody with a bassline and drum pattern.”

“Transpose this Piano Roll part up an octave and humanize the velocities.”

“Estimate the tempo and key of this sample.”

“Transcribe this monophonic melody into a reviewable note sequence.”

Generate deterministic chord progressions, melodies, bass parts, and drums from a musical brief; melody, bass, and drum generation also accept reproducible seeds. Export separate parts in one Type-1 MIDI file and verify the written file's structure and content digest. Audio tools can estimate tempo and a global major or minor key, while monophonic transcription creates a note sequence that can be reviewed and exported in a separate step.

PostFader can also find and prepare a pattern FL Studio reports as empty, add section markers, organize Playlist tracks, record a supported automation value, and prepare Piano Roll append, replace, quantize, transpose, humanize, duplicate, delete, or clear operations. Piano Roll application uses FL Studio's separate script workflow, so PostFader reports the evidence it actually has instead of claiming controller-side note readback.

From one request to a complete production workflow

[!TIP] You ask: “The vocal feels buried. Find the most likely cause, show me what you would change, and fix only the highest-confidence problem.”

PostFader workflow

1. Reads the mixer, routing, and relevant loaded plug-ins.
2. Analyzes the bounce or synchronized renders you provide.
3. Reports possible level, tonal, dynamics, or synchronized-input masking findings.
4. Your AI prioritizes the reported evidence and builds a reviewable plan from supported operations.
5. Keeps the plan separate until you choose to proceed with the apply call.
6. After you explicitly confirm that you are present and enable session writes, sends the separate apply request.
7. Reports the observed result and any evidence limitation.

Read the project → analyze the bounce → identify the problem → propose a plan → choose the change → apply → report

A narrow remote control stops at individual commands. PostFader connects those commands into a production workflow.

Feature depth

Mix and finish

• Run Mix Doctor on an exported bounce.
• Compare loudness and tonal balance when candidate and reference inputs align and pass readiness checks.
• Examine synchronized vocal and instrumental renders for possible spectral overlap.
• Measure peaks, loudness, dynamics, tonal balance, and stereo behavior.
• Watch sampled mixer peaks during a chosen observation window and build gain-staging plans.
• Run a finish assessment and use your AI to turn selected recommendations into reviewable one-shot plans.

Control the session

• Work with mixer inserts, sends, routing, and transport.
• Inspect and organize Channel Rack generators, patterns, and Playlist tracks.
• Read undo/redo history bounds and edit the current step sequence.
• Discover and control supported parameters exposed by loaded effects and generators.

Create music

• Generate deterministic chord progressions; melody, bass, and drums also accept reproducible seeds.
• Export multi-track Type-1 MIDI and verify the written content.
• Estimate tempo and global major or minor key from an audio file.
• Turn monophonic audio into a reviewable note sequence.

Edit and arrange

• Append, replace, quantize, transpose, humanize, duplicate, delete, or clear Piano Roll material through the separate FL Studio script workflow.
• Find and prepare patterns FL Studio reports as empty, add section markers, organize Playlist tracks, and record supported automation values.

Bring your own AI

• Claude: Claude Desktop and Claude Code
• Codex: CLI, IDE extension, and desktop Codex
• Cursor: IDE and CLI
• OpenCode
• Grok Build
• T3 Code through an MCP-capable provider
• Other local hosts compatible with stdio MCP servers

More than a basic FL Studio MCP

To make the distinction concrete, the baseline below is deliberately defined as a local MCP with transport commands, individual controls, point-in-time reads, predefined parameter mappings, and note dispatch. It is not a survey of every other project.

Quick installation

1. Download and extract the matching platform package.
2. Run the guided installer and select your virtual MIDI endpoint.
3. Complete the documented FL Studio MIDI Settings stage.
4. Connect your local AI client.

• Download PostFader for Windows
• Download PostFader for macOS
• Open the complete setup and troubleshooting guide
• See every v0.20.0 release asset

Codex users can choose the dedicated Codex ZIP for guided codex mcp add registration. Claude Desktop users can add the .mcpb after completing the same platform setup. Advanced users can install the wheel or source archive.

[!NOTE] Codex ZIPs, the Claude Desktop MCPB, wheel, and source archive still use the Universal Bridge, a virtual MIDI endpoint, and the documented FL Studio setup. PostFader does not install virtual MIDI software.

Python 3.10–3.14 is required. Python 3.13/3.14 or Windows ARM64 may require a native compiler for python-rtmidi.

Supported AI clients

PostFader runs as a local stdio MCP server, so the AI host must be able to launch it on the same computer as FL Studio.

Grok on the web and Grok Bot require a publicly reachable remote HTTP MCP server and cannot use PostFader's current local packages directly.

Supported systems

The v0.20.0 release notes record the exact qualification revision, acceptance counts, restoration evidence, and boundaries.

How it works

flowchart LR
    A["Your AI client<br/>(MCP)"] --> B["PostFader<br/>runs locally"]
    B -->|"Virtual MIDI"| C["Universal Bridge<br/>inside FL Studio"]
    C --> D["Your open project"]
    B -->|"Files you choose"| E["Exported audio<br/>analysis"]
    B --> F["Mix and creative<br/>workflows"]
    F -->|"Type-1 MIDI"| G["Generated MIDI files"]
    F -->|"Optional script"| H["FL Piano Roll"]

The AI client calls PostFader's named MCP tools. Live FL Studio communication travels over a local virtual MIDI endpoint to the Universal Bridge controller script. Audio tools analyze files you select because FL Studio's scripting API does not expose its live audio buffer.

Built for real projects without pretending FL Studio exposes more than it does

• PostFader starts read-only; write access lasts only for the current session.
• It never saves the project automatically.
• Supported direct changes are read back from FL Studio after they are made.
• Workflows with narrower evidence say so instead of reporting full verification.
• PostFader runs locally, requires no PostFader account, and has no PostFader telemetry.

For the exact boundaries, read What “verified” means, the write response contract, the security policy, and FL Studio API limitations.

What “verified” means

For a supported direct change, PostFader checks the target and current session, asks FL Studio to make the change, waits for a later controller update, and reads the control again. verified: true means the requested control state was observed afterward. It does not prove the choice sounds good or guarantee an undo point or rollback.

Writes affect the open project immediately. Ask the AI client to enable write mode only when you want changes, use a blank or disposable project for the first write test, and disable write mode when you are done.

Documentation

Detailed limitations

PostFader does not currently:

• guarantee rollback or an FL Studio undo point;
• save, render, or export an FL Studio project;
• hear or capture FL Studio's live audio output;
• insert, remove, or reorder plug-ins;
• reliably control an effect slot's bypass or wet/dry mix;
• create, move, or delete Playlist clips through the public scripting API;
• read Piano Roll notes back after the focus-sensitive script workflow;
• read section-marker times or recorded automation points back from FL Studio;
• infer named competing project tracks from a full-mix masking measurement; or
• turn technical measurements into objective artistic truth.

Batch application is bounded but not atomic: earlier changes are not rolled back if a later operation cannot be verified. A lost or ambiguous mutation response is never replayed automatically. The local virtual MIDI bus is shared and unauthenticated, so use PostFader on a trusted, single-user workstation.

Audio and mix tools analyze files you explicitly select or recent bounces found in bounded FL Studio folders. Results can include paths, hashes, and measurements, but never audio samples. Your AI client is separate software and may send tool arguments and results to its model provider; review that client's privacy policy before using sensitive projects.

Contributing

Read CONTRIBUTING.md for the development workflow. To help expand real-world plug-in evidence, review the definitions and target backlog in the plug-in matrix, then submit a privacy-safe plug-in validation report.

Community setup help, workflow notes, feature ideas, and compatibility results belong in GitHub Discussions.

Security reporting

[!IMPORTANT] Do not open a public issue for a suspected vulnerability. Follow the private reporting instructions in SECURITY.md.

License

PostFader is available under the Apache License 2.0. See NOTICE for attribution details.