Daily Blender Tip 168: Flipping normals on multiple objects

Jan van den Hemel writes:

In Blender 2.8 you can work on multiple objects in Edit Mode, but today I had to work on an old 2.79 file and a lot of objects in it had flipped normals. Because I didn’t feel like flipping them one by one, I searched for a solution and found this free and easy to use add-on by Alexey Khlystov.