Griddy is a tool in the Motion Dock that puts a layout grid on your comp as real After Effects guides. Columns and rows, with a gutter between them and margins around them, land in one click. Your layers snap to them like any guide. Griddy only places guides. It never moves a layer.
The top bar shows the grid's columns and rows, here 4 × 3, then the comp's size and how many guides it has.
Below it is a preview of the comp with its grid. Drag in the preview to change the margins and the gutter.
The six tiles put the grid on and take it off, add or remove columns and rows, and add other guides.
The grid is live
Once a comp has a grid, every change you make reaches the comp at once. Add a column, drag a margin or type a new gutter, and Griddy rewrites the grid’s guides. Each change is one undo step.
Griddy only rewrites the guides its grid placed. Guides you dragged out yourself, and guides from Thirds or Bounds, stay where they are.
Each comp keeps its own grid. Switch comps and the preview shows that comp’s grid, or a faint copy of the last grid you used when the comp has none.
More than a grid
Thirds adds rule of thirds guides. Shift-click it for the golden ratio, or Alt-click it for a cross through the center.
Bounds adds guides along the edges and centers of the selected layers.
Clear removes guides.
Griddy is free, inside the Motion Dock. Put your first grid on a comp to try it.