If you use Bootstrap 4 (or Bootstrap 3) on your website, Bootstrap Editor allows you:

- Add Bootstrap widgets to your content
- Preview mobile content using Bootstrap breakpoints
- Build content layout (containers, rows and columns)

Bootstrap Editor is an add-on for CKEditor you can use as an editor. You also need N1ED as Bootstrap Editor is a part of its ecosystem.

https://www.drupal.org/project/bootstrap_editor