Image optimizer

There’s this one that’s free: https://wordpress.org/plugins/ewww-image-optimizer/

as well as several other free ones: https://wordpress.org/plugins/search.php?q=Image+Optimizer

EWWW Image Optimizer does have an option to “purchase an API key to unlock additional compression levels.”

They also have a separate cloud service, which does all the processing on their end, thus saving your server resources, and of course that costs money.

If you don’t mind using the plugin on your own server, and you don’t need further compression levels, EWWW Image Optimizer is 100% free to use.