What is GIMP?

GIMP is an excellent cross-platform image editor: Windows, macOS and any GNU/Linux distribution.

It is a full-featured software, strictly open-source and free.

Perfect for trying to create a “collage” of overlapping or side-by-side images, even with different sizes, and export the result as a single image in .jpg or .png format.

Side-by-side and overlapping images

I have repeatedly needed to “blend” several images side by side or overlapping.