Discover · not made by us, picked by us
SSquoosh
Shrink an image without guessing.
FreeWebimages · websites
✓Why we picked it
A split-screen slider showing the original against the compressed version at whatever quality you pick, so you stop guessing at export settings. Everything happens in the browser, so the image is never uploaded.
◇The catch
One image at a time, no batch mode, and development has been quiet for a while.
Icon © the Squoosh team, from their public site. Listed free, no payment, no affiliation.