handplane is a new tool designed with the goal the of solving tangent space mismatch issues for everyone. handplane works by combining an object space normal map with a lowpoly model to create and engine specific tangent space map. This means that artists can continue using their existing baking software to create tangent space normal maps synced to the following engines:

3dsmax
Maya
Unreal
Source
Unity

Baking and displaying tangent space normal maps can be thought of as an encoding and decoding process. For everything to work correctly, the specific math used to bake the normal map needs to match how the game engine renders the normal map. Unfortunately, most baking tools and game engines use a unique approach. This mismatch can be seen as shading errors on your models. If you have baked normals before you have seen these errors in the form of gradients and lighting artifacts. To fix these problems artists need to use additional geometry in the form of supporting loops or smoothing splits- both of which inflate the vertex count of the asset.