Check Licenses

A simple tool to check all the licenses in your dependencies:

• Find all dependencies and their sub-dependencies in your project
• Validate both the package.json and the LICENSE file per dependency
• Only reads dependencies and not devDependencies
• Uses package-lock.json for deterministic resolution
• Handles multiple versions of the same library just fine

Getting started

You can either use npx check-licenses, or install this library globally and then run it at once:

npm i check-licenses -g
licenses   # Note how this is just `licenses`
licenses --list
licenses --help

# Or use the library straight from npm
npx check-licenses
npx check-licenses --list
npx check-licenses --help
npx --yes check-licenses   # To avoid being asked to install it, e.g. in a CI

The main command will trigger a license summary:

$ licenses
MIT —————————————————— 56
ISC —————————————————— 7
CC0-1.0 —————————————— 4
BSD-2-Clause ————————— 2
Apache-1.0 ——————————— 2
Apache-2.0 ——————————— 2
CC-BY-3.0 ———————————— 1

If you want to dig deeper and see which package uses what license, use the --list flag.

Show the licenses used

The base command is to count how many licenses of each type are in use:

$ licenses
MIT —————————————————— 1328
ISC —————————————————— 113
CC0-1.0 —————————————— 36
BSD-3-Clause ————————— 36
Apache-2.0 ——————————— 5
BSD-2-Clause ————————— 3
Zlib ————————————————— 1
CC-BY-3.0 ———————————— 1
GPL-2.0 —————————————— 1

List all dependencies

This can be used to find out what each of our dependencies (direct and indirect) is using. It might list multiple licenses in a single package:

$ licenses --list
...
test-exclude@5.2.3 ————————————— ISC
text-table@0.2.0 ——————————————— MIT
textarea-caret@3.0.2 ——————————— MIT
throat@4.1.0 ——————————————————— MIT
through@2.3.8 —————————————————— Apache-2.0 + MIT
through2@2.0.5 ————————————————— MIT
thunky@1.1.0 ——————————————————— MIT
timers-browserify@2.0.11 ——————— MIT
...

This list is normally quite long, but it can be easily grep-ed. For example, to find all of the Apache-2.0 licenses:

$ licenses --list | grep Apache-2.0
fb-watchman@2.0.1 —————————————— Apache-2.0
forever-agent@0.6.1 ———————————— Apache-2.0
formik@2.1.5 ——————————————————— Apache-2.0 + MIT
harmony-reflect@1.6.1 —————————— Apache-2.0 + MPL-1.1
human-signals@1.1.1 ———————————— Apache-2.0

If there are multiple licenses in a library it's marked with a +. You can indeed also grep that!

$ licenses --list | grep +
...
are-we-there-yet@1.1.5 ————————— ISC + MIT
atob@2.1.2 ————————————————————— Apache-2.0 + MIT
detect-node@2.0.4 —————————————— ISC + MIT
electron-to-chromium@1.3.534 ——— ISC + MIT
formik@2.1.5 ——————————————————— Apache-2.0 + MIT
fs.realpath@1.0.0 —————————————— ISC + MIT
harmony-reflect@1.6.1 —————————— Apache-2.0 + MPL-1.1
json-schema@0.2.3 —————————————— AFLv2.1 + BSD
killable@1.0.1 ————————————————— ISC + MIT
lodash-es@4.17.15 —————————————— CC0-1.0 + MIT
lodash.memoize@4.1.2 ——————————— CC0-1.0 + MIT
...

Finding bad licenses

Let's say you run this tool and find the dependencies, of which you really don't want to follow CC-BY-3.0:

$ licenses
DOC —————————————————— 56
MIT —————————————————— 56
ISC —————————————————— 7
CC0-1.0 —————————————— 4
BSD-2-Clause ————————— 2
Apache-1.0 ——————————— 2
Apache-2.0 ——————————— 2
CC-BY-3.0 ———————————— 1

Then you can also use it to track down which dependencies have this license:

$ licenses --list | grep CC-BY-3.0
spdx-exceptions@2.3.0 ——————— CC-BY-3.0

With this information you can either:

• Dig deeper: some times it might be dual-licensed
• Find out where this comes from with npm ls:

$ npm ls spdx-exceptions
check-licenses@0.2.0 /home/francisco/check-licenses
└─┬ meow@8.0.0
  └─┬ normalize-package-data@3.0.0
    └─┬ validate-npm-package-license@3.0.4
      └─┬ spdx-expression-parse@3.0.1
        └── spdx-exceptions@2.3.0