What is arrangementLab?
arrangementLab is a visual composition tool for producers and songwriters. It turns your ideas — a loop, a reference track, or just a genre — into a full song structure you can see, rearrange, and build around.
Think of it as an infinite whiteboard for your music. Every section of your song lives on the canvas as a card. Each card carries production guidance, energy data, and coaching tips. You move them, connect them, and work through them until you have a finished arrangement — not just a loop.
The goal is simple: take you from an 8-bar idea to a finished track. Everything in the app is designed around that single outcome.
Three Ways to Start
Every session begins with one of three entry points. Each one is smarter than it looks.
I Have a Beat or Loop
Drop in your audio. The analyzer detects BPM, key, energy profile, genre, and loop role — then proposes a full arrangement built around your specific sound. Not a generic template. Yours.
I Love This Song
Search any published track and reverse-engineer how it's built — section by section, bar by bar. Use it as a blueprint for your own arrangement. Study what makes it work.
Just Get Me Started
Pick a genre, set a target duration, choose your energy curve. Get a complete arrangement on the canvas in seconds. Edit anything you don't like.
In the Smart Generator, the Energy Curve setting changes the shape of your arrangement — Dynamic builds momentum and peaks at drops/choruses, while Steady keeps intensity consistent. This affects bar count distribution across sections, not just labels.
Navigation & Tools
Most of what you'll spend time in. The canvas is more capable than it appears at first.
Moving Around
Middle mouse button activates panning without switching tools. Keep your left hand on the keyboard and navigate with the mouse button — no mode switching needed.
Selecting & Editing
Click any section card to select it. Drag a box across multiple cards to select them all at once. Once selected, drag the group as a unit.
Double-click on any empty canvas area to instantly create a new section card at that position. It's the fastest way to build out your arrangement freehand.
Snap to Grid
The grid snap toggle (toolbar, top right) aligns all dragged sections to a 20px grid. Turn it on when you want clean, aligned layouts. Turn it off for freeform positioning.
Section Cards — What's On Them
Each card is doing more work than it looks like. Here's everything packed into a section card:
Energy Level
Every section carries an energy percentage — automatically set from your loop analysis or template, editable by you. Color codes the card and feeds into the coaching sidebar's energy arc.
Color Customization
Click the color dot on any card to open a palette of 12 predefined color schemes. Use color to visually group sections — all your choruses one color, all verses another.
Status Badge
Every card has a status — Not Started, In Progress, Done. Click it to cycle through. The accountability widget tracks completions against your goals.
Element Tags
The instrument/element field tracks what's playing in each section — kick, vocal, pad, synth. These feed into the mockup preview engine and the coaching Sound tab.
When you rename a section, the section type auto-updates. Rename "Block 1" to "Chorus" and the card re-classifies itself — updating energy defaults, guidance tips, and coaching content automatically.
Connectors & Arrows
Arrows do more than connect cards visually. They encode the flow of your arrangement — and they're customizable.
Press C to activate connect mode. Your cursor changes.
Drag from one section card to another. The arrow snaps to the nearest connection handle (top, right, bottom, left).
The arrow routes itself automatically — no diagonal lines, always clean orthogonal paths.
Right-click any arrow to open a color picker. You can color-code your connections — use red for tension, green for resolution, gray for standard flow. The color toolbar also lets you delete the arrow without selecting it first.
Keyboard Shortcuts
The full shortcut map. Most users don't know half of these exist.
Production Coaching Sidebar
The coaching sidebar is the most underused feature in the app. Open it with Shift + C or the Coach tab on the right edge. Select any section card to load its guidance.
The sidebar has four tabs:
DAW Tab — Your Action Checklist
A step-by-step production checklist specific to this section's type and genre. Each step is checkable — the sidebar tracks your progress per section and shows a completion counter. When all steps are checked, "Mark Complete & Next" lights up green and jumps to the next section.
Coaching progress is saved per section, not globally. Come back to a section tomorrow and your checklist is exactly where you left it — checked steps and all.
Mix Tab — Technique Cards
Genre-specific mixing techniques for this section. Not generic advice — tips are calibrated to your genre family and energy level. A chorus in a DnB track gets different guidance than a chorus in folk. Each card names the technique (e.g., "LCR panning," "sidechain ducking") so you can research it further.
Sound Tab — What's Playing
Lists the elements detected or tagged in this section — kick, snare, pads, leads, vocals. Also surfaces reference tracks curated to match this section's type and energy. Use these as actual A/B references while you mix.
Flow Tab — The Big Picture
A horizontal bar chart of your entire arrangement — every section shown as a proportional block, color-coded by energy level. Click any block to jump directly to that section's coaching. Below it: a transition tip for the boundary between this section and the next, and an energy arc graph showing how your track breathes (previous → current → next).
Use the Flow tab to spot energy problems before you're deep in production. If three sections in a row are all at 85%, your track will feel flat — fix the arrangement now, not after you've built it out.
Loop Analyzer — Your Beat → A Finished Track
This is the most powerful entry point in the app and the most underexplored. The Loop Analyzer takes any audio file and runs a full analysis pipeline — client-side, no upload to any server.
What It Detects
BPM & Key
Cooley-Tukey FFT analysis detects your tempo and key signature. Used to ensure every section of your generated arrangement stays in time and in key.
Energy Profile
5 frequency bands analyzed: bass, mid, treble, percussive, melodic — plus overall energy. Determines how high-energy your loop sits and what it's built from.
Genre & Loop Role
Primary and secondary genre guesses, plus what role your loop plays — Drums, Bass, Melody, Chords, Perc, Synth, Vocal, Ambience. Feeds into section guidance.
Reference Matches
Automatically finds 5 similar tracks from a curated reference library based on your BPM, key, and energy. Real songs to reference while you build.
The analyzer has a Manual Mode — if you already know your section names and bar counts, skip the audio analysis entirely and type them in directly. Useful for importing existing arrangements or sketching from memory.
Arrangement Preview — Hear the Idea
After a loop analysis, you can play back your arrangement using your own audio. This isn't AI generation — it's your loop processed through the arrangement you've built.
The preview engine applies different treatments per section type:
- Intro — Low-pass filtered, reduced gain, muted percussive elements
- Build — Filter opens progressively, gain ramps up, adds synthesized riser + snare roll at transition
- Drop / Chorus — Full bandwidth, 100% gain, impact FX at entry point
- Verse — Mid-range filter, muted leads and hats, reduced gain
- Breakdown — Heavy filtering, mid/side contrast processing
The preview is intentionally lo-fi — mono, low-pass capped, with periodic reference tones. It's a structural preview tool, not a production render. The point is to hear whether the arrangement makes sense, not to export a master.
Lyricist Sketchpad
Open from the right panel LYRICS tab or the toolbar. A tabbed writing environment — one tab per section in your project.
Rhyme Helper
As you write, the rhyme helper surfaces suggestions in real time. It uses phonetic matching — not just visual rhymes. Type the last word of a line and rhymes appear automatically on the right side of the sketchpad.
The line counter is live — it updates as you type. Useful for matching syllable count and structure between sections. A chorus with 4 lines and a verse with 8 lines will feel unbalanced. Watch the counter.
Focus Mode & Goals
The accountability panel (FOCUS tab) is the feature most likely to actually get you to a finished track. It's not a timer — it's a full goal and velocity system.
Goals & Deadline
Set a target completion date and the number of sections you want to finish. The system tracks progress against that target automatically.
Velocity Prediction
Based on your last 4 weeks of sessions, the system projects your actual completion date. If you're behind, it tells you. Honest feedback.
Streak Tracking
Current and longest streak tracked automatically. Sessions are logged whenever you have the app open — even background tabs count.
Accountability Partner
Add a partner's email to loop them in on your progress. Useful if you work with collaborators or just need someone to keep you honest.
Session data is stored for 90 days of history. The velocity prediction pulls a 4-week rolling average — meaning it gets smarter the more you use it. New users will see placeholder projections until a few weeks of data accumulates.
Saving, Exporting & Importing
Auto-Save
arrangementLab saves your project automatically every 2 seconds while you work. You'll see a save status indicator in the top bar — Saved / Saving / Unsaved. You don't need to hit save.
Export Your Project
The export button (toolbar) downloads your project as an .arrlab.json file. This file contains everything — canvas layout, section guidance, lyrics, goals, comments, coaching progress, change log. Open it on any device, share it with a collaborator, or keep it as a backup.
The export includes a MIDI export option — converts your arrangement into a MIDI file where each section is represented as a note event with correct duration and tempo markers. Drop it into your DAW as a structural guide.
Import a Project
From the welcome screen, click "Open Project" and select your .arrlab.json file. The app validates the file format and restores your entire session — including the canvas view position you were in when you exported.
Frequently Asked Questions
Do I need to be online to use arrangementLab?
Once you've activated your license, the app works offline. Audio analysis and reference track search require an internet connection, but the canvas, coaching, lyrics, and goals all work locally.
I lost my license key — how do I find it?
Your key was emailed by Polar when you purchased. Search your inbox for "Polar" or "arrangementLab license." If you can't find it, log into your Polar account at polar.sh to retrieve it. Once re-entered, the app remembers it on that browser permanently.
Will my projects sync across devices?
Not automatically — projects are stored in your browser's local storage. To move a project to another device, export it as an .arrlab.json file and import it on the new device. Cross-device sync is on the roadmap.
Why does the arrangement preview sound lo-fi?
By design. The mockup engine applies filters, mono collapse, and reference tones to create a structural sketch — not a production render. It's meant to help you hear whether your arrangement makes sense, not to export a finished mix.
What audio formats does the Loop Analyzer accept?
MP3, WAV, AIFF, and OGG. Files are analyzed entirely in your browser — nothing is sent to a server. Keep files under 50MB for best performance.
Can I use arrangementLab for songwriting without any audio?
Absolutely. Use "Just Get Me Started" to generate a structure from a genre, then build from there. The canvas, lyrics sketchpad, coaching tabs, and goals system all work without any audio file.
Email support@arrangementlab.com — Tom reads every one.