node package manager


NPM License Checker

Ever needed to see all the license info for a module and it's dependencies?

It's this easy:

npm install -g license-checker

mkdir foo
cd foo
npm install yui-lint

You should see something like this:

├─ cli@0.4.3
│  ├─ repository:
│  └─ licenses: MIT
├─ glob@3.1.14
│  ├─ repository:
│  └─ licenses: UNKNOWN
├─ graceful-fs@1.1.14
│  ├─ repository:
│  └─ licenses: UNKNOWN
├─ inherits@1.0.0
│  ├─ repository:
│  └─ licenses: UNKNOWN
├─ jshint@0.9.1
│  └─ licenses: MIT
├─ lru-cache@1.0.6
│  ├─ repository:
│  └─ licenses: MIT
├─ lru-cache@2.0.4
│  ├─ repository:
│  └─ licenses: MIT
├─ minimatch@0.0.5
│  ├─ repository:
│  └─ licenses: MIT
├─ minimatch@0.2.9
│  ├─ repository:
│  └─ licenses: MIT
├─ sigmund@1.0.0
│  ├─ repository:
│  └─ licenses: UNKNOWN
└─ yui-lint@0.1.1
   ├─ licenses: BSD
      └─ repository:

An asterisk next to a license name means that it was deduced from an other file than package.json (README, LICENSE, COPYING, ...) You could see something like this:

└─ debug@2.0.0
   ├─ repository:
   └─ licenses: MIT*


  • --production only show production dependencies.
  • --development only show development dependencies.
  • --unknown report guessed licenses as unknown licenses.
  • --onlyunknown only list packages with unknown or guessed licenses.
  • --json output in json format.
  • --csv output in csv format.
  • --csvComponentPrefix prefix column for compoment in csv format.
  • --out [filepath] write the data to a specific file.
  • --customPath to add a custom Format file in JSON
  • --exclude [list] exclude modules which licenses are in the comma-separated list from the output
  • --relativeLicensePath output the location of the license files as relative paths


A list of licenses is the simples way to describe what you want to exclude.

You can use valid SPDX identifiers. You can use valid SPDX expressions like MIT OR X11. You can use non-valid SPDX identifiers, like Public Domain, since npm does support some license strings that are not SPDX identifiers.


license-checker --json > /path/to/licenses.json
license-checker --csv --out /path/to/licenses.csv
license-checker --unknown
license-checker --customPath customFormatExample.json
license-checker --exclude 'MIT, MIT OR X11, BSD, ISC'
license-checker --onlyunknown

Custom format

The --customPath option can be used with CSV to specify the columns. Note that the first column, module_name, will always be used.

When used with JSON format, it will add the specified items to the usual ones.

The available items are the following:

  • name
  • version
  • description
  • repository
  • publisher
  • email
  • url
  • licenses
  • licenseFile
  • licenseText
  • licenseModified

You can also give default values for each item. See an example in customFormatExample.json.


var checker = require('license-checker');
    start: '/path/to/start/looking'
}, function(err, json) {
    if (err) {
        //Handle error 
    } else {
        //The sorted json data 


license-checker uses debug for internal logging. There’s two internal markers:

  • license-checker:error for errors
  • license-checker:log for non-errors

Set the DEBUG environment variable to one of these to see debug output:

export DEBUG=license-checker*; license-checker
scanning ./yui-lint
├─ cli@0.4.3
│  ├─ repository:
│  └─ licenses: MIT
# ... 

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