Bootstrap 4.4.1

The built assets with popper.js for Drupal 8 composer install

To use in your theme, add this into your libraries yml

bootstrap:
  version: 4.4.1
  css:
    component:
      ../../../libraries/bootstrap/css/bootstrap.min.css: {}
  js:
    ../../../libraries/bootstrap/js/bootstrap.min.js: {}
  dependencies:
    - core/jquery
    - your_theme/popper

popper:
  version: 1.16.0
  js:
    ../../../libraries/bootstrap/js/popper.min.js: {}
  dependencies:
    - core/jquery

In your theme.info.yml

libraries:
- your_theme/popper
- your_theme/bootstrap