FileProInfo - It's All About Files, Software, Online Tools - 100% Free
Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.
File-Extensions.org - Large computer file extension library with detailed explanation of each file type with links to download free or associated software programs.
Wondershare PDFelement - All-in-one PDF editor
GroupDocs - GroupDocs is a web-based service for online document sharing, collaboration and management.
Foxit Reader - Foxit Reader is a free and light-weight multi-platform PDF document viewer.