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.

Workflows 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.

On macOS, plugins_list_available reads FL's native Add menu and plugins_load adds an instrument or an effect on a specified mixer track, then identifies the new instance through FL's bridge. Removal and reordering remain unavailable, as does reliable effect-slot bypass or wet/dry control.

Plugin Atlas adds offline product knowledge for plug-ins whether or not an instance is currently loaded. Its bundled Image-Line catalog and selected third-party records describe purposes, techniques, limitations, and explicit stock alternatives. Atlas keeps that knowledge separate from runtime matching, control-adapter evidence, and the three honest availability states. See the Plugin Atlas guide or inspect the installed bundle with postfader-plugin-atlas.

🎚️ Choose a coherent sound palette

“Create a melodic bass track and choose all the sounds yourself.”

“Keep the lead in Drop B, but make the bass and texture feel bigger.”

Sound Selection turns that direction into a deterministic palette chosen from the generators and effects already loaded in the project. It can select a product and exact preset for each role, preserve core identity sounds, plan a section variation, map a drum kit's reported pads, and pass role targets into a Production Run. User preferences and exclusions always win; balanced planning uses bounded local recency only to distinguish similarly suitable choices.

Sound Selection does not use random preset roulette or pretend to hear FL Studio's output. It reads preset identity back after bounded navigation, keeps explicit local feedback and usage history separate from project state, and reports a concise blocker when the requested sound is not loaded. Load the instrument pool manually, then see the Sound Selection guide for examples and exact boundaries.

🎹 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 inspect existing Piano Roll notes or prepare 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. Returns the proposed changes for a plan-only request, or uses the existing authorization when you asked it to fix the problem.
6. Enables session writes once and applies the supported changes within that request's scope.
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.

Production Runs: task-scoped autonomy

Production Runs let your connected AI turn one outcome-oriented request into a bounded, multi-stage plan. Ask it to finish a track, build around a loop, transform a genre while preserving a vocal, work only on one section, or mix without changing notes. The AI submits the structured plan; PostFader validates scope, resolves references, applies supported operations, and records truthful receipts.

Creation runs now begin with one silent readiness scorecard covering the live bridge, Piano Roll, generator pool, drum map, patterns, loaded processing, and known manual handoffs. A ready run keeps that bounded context through palette, composition, note application, processing, and finalization instead of rescanning the complete project before each change. Sound choices retain confidence and alternatives; generated notes can adapt to known articulation, envelope, register, and polyphony; supported loaded effects can be planned by semantic goal and applied through the existing verified setters.

Autonomy belongs to that request only—there is no permanent autonomous-mode toggle. A plan-only request never changes FL Studio. An authorized execution run enables the existing session write gate once, then continues until the submitted plan completes or reaches a real blocker. Earlier verified changes remain visible if a later operation fails; PostFader never claims rollback, replays an ambiguous mutation, or saves the project automatically.

The consolidated result reports technical execution, arrangement delivery, processing, manual handoff, and audible quality separately. Technical success never means PostFader heard or approved the song. See Creation pipeline, Production Runs, and Sound Selection.

See the Production Runs guide for chat examples, the supported MVP operation set, continuation and stop behavior, durable run lifetime, and FL Studio limitations.

Production Runs now survive MCP restarts: postfader_list_runs finds retained plans and receipts, and postfader_continue_run resumes remaining work. An interrupted operation with an unknown outcome is never replayed.

piano_roll_read_notes inspects existing note timing, pitch and expression through the Piano Roll script bridge without enabling musical edits. postfader_render_saved_project starts a separate WAV render from a saved .flp; inspect or cancel it through the render job tools. Unsaved live edits are not included. These new paths have synthetic coverage; live acceptance on FL Studio remains pending.

Genre requests now supply editable instrument-role defaults, with ten style profiles and eighteen instrument families. Explicit preferences stay in control.

Creation Review, Revision, and Delivery

After a Production Run creates a playable draft, export one bounce and ask the connected AI to review and improve it. PostFader validates and measures the selected file globally and by known song section, combines that evidence with your explicit feedback, protects accepted sounds or notes with independent locks, and compiles the smallest bounded revision into the existing Production Run executor. One revision pass uses one readiness preflight and one task-scoped write authorization.

Export the revised bounce with matching settings and PostFader can compare the two versions, report improvements and regressions separately, and prepare an exact Playlist, export, and delivery handoff. Technical measurements and section-energy proxies never substitute for your artistic approval. Sessions can persist locally without storing audio bytes or paths you chose not to retain. The review workflow does not save, create Playlist clips, insert plug-ins, or hear FL Studio's live output. See the Creation Review guide, which documents its 13 MCP tools and 9 corresponding Production Run operations.

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.
• Plan and apply a coherent sound palette with exact preset verification, drum-pad mapping, continuity, and bounded novelty.
• Read bundled Plugin Atlas product knowledge and compare it with observed loaded plug-ins without turning the catalog into a runtime allowlist.

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 v10.0.0 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 V10 release notes distinguish automated platform checks from the historical live qualification matrix and the remaining experimental host-adapter paths.

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; opening or reloading a project resets write access.
• 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.

FL Studio MCP questions

What is PostFader?

PostFader is an open-source FL Studio MCP server. It connects a local AI client to FL Studio through the Universal Bridge and virtual MIDI, with additional file-based audio analysis and composition workflows.

Does it work on Windows and macOS?

Yes. The release includes standard and Codex setup ZIPs for both platforms, an optional Claude Desktop MCPB, and Python packages. FL Studio, matching bridge installation, and a bidirectional virtual MIDI endpoint are required.

Which features are released?

V10 (10.0.0) exposes 134 tools and 8 resources, including Plugin Atlas, Sound Selection, recoverable Production Runs, Creation Review, Piano Roll note inspection, macOS plug-in loading, and saved-project rendering. Read the release notes for experimental feature boundaries.

Does it upload my music or save my project?

PostFader has no hosted service or telemetry and never saves your project automatically. Audio analysis runs on files you select. Your AI client may send tool arguments and results to its model provider under that client's settings. Keep private project data and local run journals out of public reports.

Documentation

Detailed limitations

PostFader does not currently:

• guarantee rollback or an FL Studio undo point;
• save an FL Studio project or render unsaved live state;
• hear or capture FL Studio's live audio output;
• insert plug-ins on Windows, or remove or reorder them on either platform;
• reliably control an effect slot's bypass or wet/dry mix;
• create, move, or delete Playlist clips through the public scripting API;
• 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.