PdfConcat.net is described as 'Applet to merge or concat several sites from pdf files. No upload limits'. There are more than 50 alternatives to PdfConcat.net, not only websites but also apps for a variety of platforms, including Windows, Mac, Linux and iPhone. The best alternative is PDF-XChange Editor, which is free. Other great sites and apps similar to PdfConcat.net are PDFsam (Freemium, Open Source), PDF24 Creator (Free), Adobe Acrobat DC (Paid) and PDF Arranger (Free, Open Source).
Elimisoft PDF Creator is a great way to help you create PDF from Word(.docx), PowerPoint(.pptx), Plain Text, RTFD, HTML, EPUB, and Image(.png, .gif, .tif, .jpeg, etc). It also keeps the origin formatting after creating!.
PDF Mixer is a PDF page tool which mixes pages of 2 or more PDF files, add PDF pages into existing PDF files and save them to a new file. With this powerful tool, you can reorder, copy, rotate, delete, switch and merge pages in multiple PDFs easily.
Free PDF Splitter Merger is a free and advanced application for splitting and merging PDF Documents and for extracting or deleting page from them. The application is simple to be used but it is also possible to set various complicated criteria.
Create, edit, view, print and annotate PDF files... for free! Some of the things that FreePDF can do for you: Rearrange the order of the pages in a PDF file, insert pages from other PDFs or remove pages.