PDFtk Server (formerly Pdftk)

PDFtk Server is the bigger more complex brother of PDFtk Free, a tool which you can use to perform a considerable number of PDF operations. It is a command line tool that is designed for advanced users as it does not offer an interactive graphical user interface.

Merge, collate, split, decrypt and watermark PDFs

The subtitle doesn't cover all of PDFtk Server’s features, the list is quite long. It has everything PDFtk Free does, and adds a lot more features which enable you to execute a large number of tasks, both basic and elaborate.
Since the application doesn’t come with a GUI, it’s intended for those who are familiar to the command line interface. Each operation you want to perform requires a specific command and PDFtk Server supplies very long list of them.
To get acquainted with all of its operations and options, all you have to do is start the app and run the standard ‘--help’ command. That should bring up a complete list of the commands you can use, as well as a description for each one.

Repair corrupted PDFs

Apart from offering built-in help, PDFtk Server also supplies online documentation with examples which should be more than enough for you to be able to use the application to its full potential.
It certainly comes in handy for cases in which you need to generate PDF data stencils, report metrics, bookmarks and metadata, unpack PDF attachments, repair some corrupted documents, encrypt files, or re-compress page streams.

A practical tool for the command line savvy

With the above to consider and a lot more to discover as you familiarize yourself with with all of its options, it’s safe to say that if you have a good handle on the command line interface, then PDFtk Server is a really good PDF manipulation tool to have.