Optimize individual images already in your media library.
Resize large original images by setting a maximum width and/or height.
Preserve copyright metadata, creation date and GPS location in the original images.
This plugin automatically optimizes all your images by integrating with the popular image compression services TinyJPG and TinyPNG.
Install this plugin and obtain your free API key from https://tinypng.com/developers.
With a free account you can optimize roughly 100 images each month (based on a regular WordPress installation).
The exact number depends on the amount of thumbnails you use.
You can change which of the generated thumbnail sizes should be optimized in the Settings > Media page.
If you’re a heavy user you can optimize more images for a small additional fee per image.
The API key can optionally be configured in wp-config.php.
This removes the need to set a key on each site individually in your multisite network.