What's known as plugin or addon in other platforms, is what we call a module in the universe. Drupal core itself is a a collection of modules as well and the community has added and maintains tens of thousands of individual modules on top of that.

CKEditor Abbreviation

module for adding and editing abbreviations in Wysiwyg CKEditor.

User Hash

The User hash module allows you to create an individual hash for each user. Use it as a light-weight user identification where you do not want to use the login credentials. E.g. as an individual API Key for reading insensitive content.