There are plenty of online and offline tools that allow you to compress PDFs and make them easier to share in different ways. However, most of these free online compressors do not allow any level of compression customization, which means you don't have any control over the extent the file is reduced to. Keep in mind that security is important when working with online tools. With offline PDF compressors, such as PDF Extra, you work locally on your desktop where security is not an issue. With PDF Extra's compression you can also decide how much the embedded images' file size will be reduced.