This is a paid asset, but now you can download UV Inspector Free.
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UV Inspector v1.2 (Latest version)
Utility to preview UV coordinates of the mesh.
Features:
– UV1, UV2, UV3, UV4
– Skinned Meshes
– Sub-Meshes
– Vertex Colors
– Isolated Texture Channel Preview
– Ability to save an image of the UV layout
– Ability to inspect uv values