ShortPixel is described as 'image optimization API and WordPress plugin that helps improve your website performance. Both lossy and lossless compression available' and is an app in the Photos & Graphics category. There are more than 25 alternatives to ShortPixel for a variety of platforms, including Online / Web-based, Mac, Windows, Wordpress and Linux. The best alternative is RIOT - Radical Image Optimization Tool, which is free. Other great apps like ShortPixel are ImageOptim (Free Personal, Open Source), TinyPNG (Freemium), JPEGmini (Paid) and Optimage (Freemium).
Crunch - Insane(ly slow but wicked good) PNG image optimization. It combines selective bit depth, color type, and color palette reduction with zopfli DEFLATE compression algorithm encoding using embedded versions of the pngquant and zopflipng PNG optimization tools.
WP Smush strips hidden, bulky information from your images, reducing the file size without losing quality. The faster your WordPress site loads, the more Google, Bing, Yahoo and other search engines will like it.
optimus.io offers lossless compression of images available with a WordPress plugin and via API. Benefits: - The file size will be reduced but the image quality remains the same - Bulk optimization - Conversion also to WebP available