If you're a designer/developer on Mac I would strongly recommend ImageOptim (https://imageoptim.com/). It supports Zopfli and has a simple drag-n-drop user interface.
http://trimage.org/
If you're a designer/developer on Mac I would strongly recommend ImageOptim (https://imageoptim.com/). It supports Zopfli and has a simple drag-n-drop user interface.