ShortPixel

ShortPixel is a veteran image optimization service with an official WordPress plugin. It has processed over 33 billion images for websites. Three compression modes: Lossy (smallest size, slight quality loss), Glossy (balanced), and Lossless (no quality loss at all). Supports automatic conversion to WebP and AVIF, modern formats that save 25-50% in weight. Billing is based on credits: each processed image equals one credit. After installation, the plugin handles all old media and every new upload in the background. Automatic backup of original images lets you roll back at any time. The free plan gives 100 credits per month, enough for small blogs. One-Time packages suit sites that upload large batches of images once. Monthly subscriptions fit active sites that publish content regularly. There is also an Adaptive Images plugin that serves images at the right size from a global CDN based on screen size. The downside: the credit model is confusing at first, and you need to track usage so you do not get stuck. Works great alongside WP Rocket and a CDN.