If you’re in the business of sending PDFs through email, you’d want to reduce the file size as much as possible. That’s where SmallPDF comes in. The site is capable of combining and shrinking PDFs from the cloud to make sending the files easier. It can also convert PDFs to other file formats and vice versa. The disclaimer of the service is they store your files for an hour so it’s best you don’t use this for confidential files.