Hi @13Flo - welcome aboard! Archimatix snapping mode is built in. When you are edit mode in FreeCurve (or anytime you have an Archimatix model selected), a menu appears at the bottom of the SceneView window. On the right side of that, you'll find a checkbox labeled "Snap". If you check that, you will be in grid snapping mode. To the right of that checkbox is a grid size field so you can adjust the granularity of the snapping. Alternatively, if you are not in grid snapping mode, if you hold down the Cntrl key it will enter grid snapping mode. Likewise, if you are in grid snapping mode, holding down the Ctrl key will temporarily relax grid snapping. This snapping also works for any handles, 2D or 3D.