Crunch is a free, open source macOS GUI application that is built on pngquant and zopflipng PNG image optimization. It uses a lossy approach to PNG image optimization. The tool is available through Homebrew as a native macOS application.
`$ brew cask install crunch`
Image examples + compression ratio analysis available on the Github repository README.
Upload your images and automatically resize them to over 50 of the required web and social media sizes with the click of a button. The Promo Image Resizer will instantly convert and adjust the image to new formats and ratios, which you can then edit and optimize further, should you want to.