Windows only: Lightweight application PDFMerge combines and splits PDF files. Specify page ranges from each document you're merging and manipulate bookmarks, too. Preserve existing document bookmarks in a new bookmark tree or omit them altogether. Run PDFMerge from the command line or from the included GUI. PDFMerge is no-frills merging program so if you are looking to do more than merge files check out previously mentioned PDFill; Mac users want Combine PDFs. PDFMerge is a free download for Windows only.