This package aim to scan your code and discover which extra packages your code is actually relying on.

Install dependency-scan running:

    $ [sudo] npm install dependency-scan [-g]

Dependency-scan can be started just running into your project folder

    $ dependency-scan

Scans all files in the current folder tree (excluding .git, .svn and node_modules) and builds a list containing every meaningful required package name.
Take care that, since the search is just done matching for arguments passed to every require function call, the resulting list could contain some names that actually comes from a frontend js. Dependency-scan will try to discover those ones and to notice You if something is found, btw is always at least wise to check the resulting list before compromising the package.json your project depend upon.