Tools for high quality GIF files

I want to add some GIF files to my README.

Please help me create some GIF files:

• merge PNG images.
• convert a video to GIF.

I have seen some 60fps 4k gif files, but I know they are fake. For example 9gag using <video> tag with an mp4 video source.

I am not able to embed video directly to my README.

I want only short (2-5 seconds) videos.

What is the best way to add animation to a github README file?

If you want a tool to record your desktop screen to gif directly, I strongly recommend ScreenToGif which is really easy and very useful.