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:

The CiviMobileAPI extension (com.agiliway.civimobileapi) is a CiviCRM component that allows to use a mobile application CiviMobile.
Current Usage: 283
This CiviCRM extension provides a daily scheduled job named "Call Email2Each.Sendemails API (Daily)"  This job expects 2 parameters: a group name and a message template name.  When this job runs,  it will send an email to each contact in the group/smart group. The contents of the email will be the message template. ...
Current Usage: 272
Extension to facilitate postcode lookup feature in CiviCRM using AFD, Civipostcode, Experian, PostcodeAnywhere or getaddress.io providers.
Current Usage: 256
Omnipay is an open source payment processor library that supports multiple payment processors (around 30 currently). https://github.com/omnipay/omnipay...
Current Usage: 255
Sagepay using the Omnipay multiprocessor extension.
Current Usage: 255
In version 4.7 and up, CiviCRM ships with only CKEditor, and other wysiwyg editors can be added via extension. This extension makes TinyMCE available as a wysiwyg editor for CiviCRM....
Current Usage: 248
CiviSEPA allows you free SEPA direct debit collections, if you are in Europe.
Current Usage: 243
This extension loads United States counties when you first install it.  Once enabled, it does nothing.  You may disable it or uninstall it, and nothing will happen: the counties will remain loaded in your database.  If you re-enable it, it will check for missing counties and just add those....
Current Usage: 235
This extension adds a pivot report that suppots multiple CiviCRM entities.
Current Usage: 221
Adds over 20 new fields to Summary Fields, including contributions by related contacts, plus fields for CiviMail, CiviEvent, and CiviGrant.
Current Usage: 209
The Advanced Fundraising extension provides a series of reports to help fundraisers view their progress in greater detail....
Current Usage: 206
Creates Tax Receipts with distribution by email or print, detailed reporting, press ready
Current Usage: 205
This extension allows a staff user to add, edit and delete line items of a contribution.
Current Usage: 202
This extension is designed to preserve the email reputation of your server and its IP by ensuring that all outbound email is sent from an address with the same domain as the System-generated Mail Settings From Email Address configured at Administer > Communications > Organization Address and Contact Info (civicrm/admin/domain?action=update&reset=1)....
Current Usage: 205
This extension allows to find and export payment(s) for contribution(s).
Current Usage: 183