Many of us use online tools and websites to merge their pdf files. People might not be comfortbale uploading their files to sites because of privacy. merge-pdf is a command line tool to merge the pdf files locally. You can pass the files as a argument and it will produce a merged single file for them.
Prerequisite : Make sure you have the npm installed in your machine. You can get the letest version of npm from here
Stable version:
Choose your favourite terminal and run the following command.
npm install -g merge-pdf$ merge-pdf inputfile-1.pdf inputfile-2.pdf
$ Successfully merged pdfs. Output : merged-file.pdf