If you want to make a PDF file smaller before you share it online, try Free PDF Compressor for Windows. All you’ve got to do to get a smaller size is just pressing the Compress button after you choose a compression profile.
There are five profiles available, each comes with information about what it can do for you. Screen profile, for instance, is optimized for on-screen reading purpose by offering the lowest image resolution, which is 72 dpi.
In a test using a 769-pages PDF file containing lots of colorful images, the program managed to reduce its size from 103 MB to aprroximately 22.6 MB using the screen profile.
Two things that you might not like. There is no portable version and it doesn’t support batch conversion. If you often need to compress multiple PDF files, perhaps this one (Windows only) can make you interested. It’s also a freeware.
Go to the developer’s homepage to download Free PDF Compressor.