What eXLib Is
eXLib is a professional IDE for writing After Effects expressions. It runs as a CEP panel inside After Effects — not a separate app, not a text field bolted onto the timeline — and gives you a real code editor, built on Monaco (the engine behind VS Code), that understands the AE expression dialect the way a full IDE understands a programming language.
An IDE that knows After Effects
A plain AE expression field is a text box that runs your code and shows you a red triangle when something's wrong. eXLib knows what you're writing:
- It highlights AE globals and functions distinctly from your own variables.
- It autocompletes real AE properties — including the actual layer and effect names in your open composition, not a static list.
- It documents built-in AE symbols on hover — signature, description, and example code — from a generated type registry rather than a hand-written cheat sheet.
- It validates your code against how After Effects actually runs it — not a textbook JavaScript spec.
Beyond the editor, eXLib ships a full Expression Library — a pre-populated, organizable corpus of 100 expressions across 15 categories, ready to search, audition non-destructively against your live selection, and apply in one click, creating whatever Slider, Color, or Checkbox controls the expression needs along the way.
These screenshots were captured in an earlier beta. Toolbar and Library layouts have since changed; the written instructions on this page describe v0.145.4. See A Tour of the Panel for the current controls.
The four ideas you'll meet everywhere
Four concepts recur throughout the rest of this documentation. Getting comfortable with them now makes everything else click faster.
- Non-destructive audition — preview any expression on your real property and see AE's genuine verdict, with a guarantee the property is restored exactly as it was.
- Variables — turn magic numbers and layer references into named, wired placeholders, and generate real AE effect controls (or a whole pseudo effect) when you apply.
- Live host awareness — the panel knows what property, layer, and comp you have selected in AE right now, and uses that everywhere: autocomplete, the status bar, Apply, Audition. It can also read any other composition in the project without moving After Effects off the one you're working in.
- Pinning — lock a tab's Apply target to a specific property so it always wins over your live AE selection, even while you browse or edit elsewhere.
Who it's for
eXLib is for motion designers who write expressions daily and want IDE-grade help doing it, and for teams who want a shared, curated library of proven expressions with a safe way to apply them.
Where to go next
Start with Install & First Launch to get the panel open, then install the native companion — it's a required second step, not an optional accelerator. A Tour of the Panel names every region so the rest of this guide can point at them directly.
Once the panel is open, Workflows is the fastest way in: six jobs you already do in After Effects, written twice — the plain AE path, and the same job here.