What are some alternatives?
When comparing Imagify and WP Smush, you can also consider the following products
imgix - Real-time Image Processing. Resize, crop, and process images on the fly, simply by changing their URLs.
TinyPNG - Make your website faster and save bandwidth. TinyPNG optimizes your PNG images by 50-80% while preserving full transparency!
Piio - Generates responsive images so you don't have to optimize
Yoast Plugins - Yoast offers plugins to improve SEO and optimize web sites and blogs.
Cloudinary - Cloudinary is a cloud-based service for hosting videos and images designed specifically with the needs of web and mobile developers in mind.
ImageOptim - Faster web pages and apps.