I recently launched Clop Pro, and thought to share it with fellow MacRumors readers here ^_^
It's a small app that sits in the background and waits for you to copy an image (e.g. screenshot to clipboard) and then optimises it automatically so that you can paste a more size-efficient image in chats, emails, upload boxes etc.
It can also watch specific folders for images and videos to be dropped, and then optimises them and shows the result as a drag-and-droppable thumbnail.
It also has a global drop zone so you can manually optimise any file by dragging and dropping it there:
Website: https://lowtechguys.com/clop
Source code: https://github.com/FuzzyIdeas/Clop
Pricing: Free for clipboard optimisations and 2 file optimisations per session, $8 for unlimited file optimisations