This plugin allows you to optimize your WordPress images through the Kraken.io API, the world's most advanced image optimization and resizing API …
This plugin enables you to automatically resize every user-posted image which is larger than given dimensions.
Auto resize/convert image uploads to set height/width or file type. Auto set image alt, title tags, limit file size and disable 2560px limit.
Browser Resize Images
A WordPress plugin for client-side uploaded images resize (to do it client-side instead of backend-side and minimize the backend performance hit).