How to Add Third-Party Libraries to Composer in Drupal 8

Blazy

composer.json

"blazy/blazy" : {
  "type": "package",
  "package": {
  "name": "blazy/blazy",
  "version": "v1.8.2",
  "type": "drupal-library",
    "dist": {
      "url": "https://github.com/dinbror/blazy/archive/master.zip",
      "type": "zip"
    }
  }
},

"require": {
  "blazy/blazy": "^1.8.2",

Slick

composer.json

"blazy/blazy" : {
  "type": "package",
  "package": {
  "name": "blazy/blazy",
  "version": "v1.8.2",
  "type": "drupal-library",
    "dist": {
      "url": "https://github.com/dinbror/blazy/archive/master.zip",
      "type": "zip"
    }
  }
},

"require": {
  "slick/slick": "^1.8.1",

CKEditor Templates

composer.json

"ckeditor-plugin/templates": {
  "type": "package",
  "package": {
    "name": "ckeditor-plugin/templates",
    "version": "4.14.1",
    "type": "drupal-library",
    "vendor": "ckeditor-plugin",
    "dist": {
      "url": "https://download.ckeditor.com/templates/releases/templates_4.14.1.zip",
      "type": "zip"
    },
    "require": {
      "composer/installers": "~1.0"
    }
  }
}

"require": {
  "ckeditor-plugin/templates": "~4.14.1",
  "drupal/ckeditor_templates": "^1.2",

Installing Required Libraries

composer update --lock