PDF Joiner - This online tool allows you to join several PDF documents into a single file, free of charge.

Google Docs - Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.

DocuPUB - DocuPUB is an online file converter, file merger, file compressor, and file resizing tool.

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.

PDFill - Open, View, Edit, Save and Print PDF Documents without Adobe Acrobat

Wondershare PDFelement - All-in-one PDF editor