Gumlet provides both levels of optimizations:
• Server side which includes compression, format conversion (to WebP and AVIF depending on end-user device OS), and CDN delivery. This typically reduces image size by 30-40%. All you need to do is plug in Gumlet URLS into src.
• Client-side which includes responsive resizing and adjustment in DPR based on end-user screen size. This further reduces image size by 20-30%. Using a web proxy (or any source type) will always apply server-side optimization automatically without any further steps. However, to get client-side optimization you must use JS integration. If you want to use JS with a web proxy you might have to do an extra step described here.