WordPress.org

A very fast caching engine for WordPress that produces static html files.

By: Donncha O Caoimh, Automattic, and Brandon Kraft.

The one plugin you need for stats, related posts, search engine optimization, social sharing, protection, backups, speed, and email list management.

By: Automattic, adamkheckler, Andrew Duthie, Alex Kirk, allendav, alternatekev, and others.

Akismet checks your comments and contact form submissions against our global database of spam to protect you and your site from malicious content.

By: Matt Mullenweg, Ryan Boren, Andy Skelton, Michael Adams (mdawaffe), and others.

BuddyPress helps site builders and WordPress developers add community features to their websites, with user profile fields, activity streams, messagin

By: John James Jacoby, Paul Gibbs, Boone Gorges, r-a-y, imath, @mercime, and others.

bbPress is forum software, made the WordPress way.

By: Matt Mullenweg, John James Jacoby, Jennifer M. Dodd, and Stephen Edgar.

A simple and easy way to test your theme for all the latest WordPress standards and practices. A great theme development tool!

By: Samuel Wood (Otto) and Simon Prosser.