Supports NPOs

This plugin offers a very clean and easy-to-use user interface. The quality of the optimized pictures in lossy mode leaves nothing to be desired, but you can also choose glossy or lossless mode, which leaves you more options than other plugins. If you have a lot of thumbnail sizes registered you need to watch your credits, but since the latest update ShortPixel allows you to exclude unused sizes.
100 Credits per month doesn’t last for long if you include your thumbnails, but the offered one-time credit packs seem to be fair-prized. And if you need image optimization for a nonprofit organization then ShortPixel will support you for free.

Together with the excellent e-mail support (a requested feature was implemented in less than seven days!) this is by far the best image optimization plugin for wordpress.