Free PDF Compressor, as the name implies, is a PDF compression app designed to shrink large PDF files.All one has to do is browse to the PDf you want to compress, then select the output location. By default, the PDF you compress will be saved in the same place with ".compressed.pdf" added to the end. By creating a second PDF file, you preserve the original PDF should you not be happy with the results. If want to test different compression methods, you will need to manually rename your other attempts as Free PDF Compressor assumes you're renaming a file once.You can choose from five settings depending on how you want your PDF compressed. By default, low-resolution, screen view quality, 72 dpi is the default. You can also choose from 150-300 dpi settings including eBook, Printer, and Prepress. Default, ironically, is the fifth and not the default selection. That setting will make a bigger file, possibly larger while keeping your pdf a better quality.In our tests, we tried all the settings and found that a 424 KB PDF only compressed to 414 KB, hardly worth the effort.Free PDF Compressor is free and easy to use. It's best used on very large PDF files to make a difference as the difference on PDF files under 5 MB was minimal at best.