Usmar UV is a Blender add-on for creating UVs.

Usmar expands functionality and speeds up the process of creating UV-map in Blender 2.8x - 2.9x.

Update 0.3: Advanced UV Maps

• Rename active for render maps of selected objects.
• Merge maps at active map (all or nearest).
• Change the map's index in the stack.
• Copy/Paste UV map to other maps of any object. You can copy/paste maps in object mode or only selected islands in edit mode.

• Find objects that contain an active UV map.

Update 0.2.5

• New features:

• Bug fixes
  
  Version 0.2:
• UV Layout:
  Pack
  Fit
  Rescale
• New Selections
• Pie menus for selections and selection mode
• Multi-object support
• UI improvement

Details:

Version 0.1 is a set of tools, including:

• quick selections
• quick transforms
• straightening
• alignment
• sorting 
• snapping
• space distribution
• boundary seams
• mirror seams
• pie menu display stratch

More details: