GIMP is just a free alternative to Photoshop. EZGIF is a website. I'd be concerned about uploading my pictures to another website and having them send them back to me. GIMP, on the other hand, is something you install on your computer, so it's never accessible to anyone else.

I used GIMP for about ten years before I could afford Photoshop.

Hello. I need to optimize jpegs to maximize my WordPress storage space. They've mentioned EZGIF.com and GIMP. Would you recommend one over the other? Do you have other recommendations? In particular, I want to be mindful of any safety/security vulnerabilities with a third party site or program. Thank you!