Find unused npm packages in package.json

There is also a package called npm-check:

npm-check

Check for outdated, incorrect, and unused dependencies.

It is quite powerful and actively developed. One of it's features it checking for unused dependencies - for this part it uses the depcheck module mentioned in the other answer.

You can use an npm module called depcheck (requires at least version 10 of Node).

1. Install the module:

    npm install depcheck -g
   
    or
   
    yarn global add depcheck
   

2. Run it and find the unused dependencies:

    depcheck
   

The good thing about this approach is that you don't have to remember the find or grep command.

To run without installing use npx:

npx depcheck