CutePDF Editor is a free, web-based application that allows you to combine two or more PDFs into one document by clicking the “Merge PDFs” button and adding your files–perfect if you do not have access to Adobe Acrobat (not to be confused with Adobe Reader). It can accommodate individual PDFs up to 5.0 MB (with no more than 1,000 pages). CutePDF Editor also includes other features such as the ability to reorder, resize, rotate, extract, crop, and delete individual pages. In addition, you can add a header and/or footer as well as password protection to your PDF.
An account is not required to use this application.
CutePDF Editor: https://editor.cutepdf.com/edit.asp