An interesting on-line image compression tool called Squoosh, best opened in Chrome as it doesn't always work well in Safari.

The reason I advocate the use of this tool is that when I run Chrome> Developers Tools> and Audit I often get reports that such and such an image is larger than it needs to be. I find that by using the output of Squoosh - the Audit tool is quite happy with the results, whereas using some other tools for compression, that is not always the case.