Berun

Snapline is a snapping and alignment add-on for Blender that speeds up object positioning. It provides real-time snapping and alignment tools for matching position, rotation, and orientation between objects with minimal effort.

SymTrz is a real-time symmetrize preview add-on for Blender's 3D View, letting artists instantly see which side will be mirrored. It provides Mirror in Object Mode and Symmetrize in Edit Mode, with a customizable hotkey and color.