Extensions are installable packages which give CiviCRM new functionality, and this directory provides a centralized list of extensions which the CiviCRM community has created.

Further resources:

This listing displays plugins specifically built to integrate with WordPress features. You can also browse directories of plugins or modules that are made specifically for Backdrop, Drupal and Joomla. The recommended way to add functionality to CiviCRM is using CiviCRM extension.

Click & Pledge Payment Processor for CiviCRM.
Keeps a WordPress user in sync with a CiviCRM membership by granting either a role or capabilities to a WordPress user who has that membership.
Provides WordPress widgets for a single event or a list of events, in the sidebar or with shortcodes.
CiviCRM Gutenberg Blocks
The CiviCRM Gutenberg Blocks plugin provides Gutenberg Editor blocks for CiviCRM Entities.
Integrates the WPForms plugin for WordPress with the Form Processor extension for CiviCRM. Allows you to submit data from WPForms into CiviCRM, even a CiviCRM located on a different site.
This is a bridge of YooThemePro (YTP) Page Builder with CiviCRM. It provides a front-end, 'drag and drop' layout builder for CiviCRM Entities, such as Contacts and Events, which are loaded as Dynamic Content custom sources into YTP. It uses CiviCRM API3, and integrates with Dynaimic Content features including filtering and sorting by field, filtering by group and content type, conditional display of fields based on any other field value, date formating & image URLs.

It is developed by Deepak Srivastava of Mountev, with the support of Joshua Gowans and Nicol Wistreich.