This free online JPEG compressor converts your lossless PNGs or high quality JPEGs into lossy JPEGs with the smallest filesize possible.
There are a lot of articles about online image compression tools in the net, most of them are very superficial. Usually they end with a simple: "It generates smaller pictures, so it's got to be better."
Learn why such statements are most of the time meaningless, understand the technical background, and find out which tool you should use as of today.
From now on compress-or-die.com/jpg always embeds the unit inch for the resolution, because the unit cm seems to be problematic for some programs (e.g. Outlook and Apple Mail).