WordPress.org

Increase your traffic, view your stats, speed up your site, and protect yourself from hackers with Jetpack.

By: Automattic, Adam Heckler, Andrew Duthie, Alex Kirk, allendav, alternatekev, in others.

Akismet checks your comments against the Akismet Web service to see if they look like spam or not.

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

BuddyPress helps you build any type of community website using WordPress, with member profiles, activity streams, user groups, messaging, and more.

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

bbPress is forum software, made the WordPress way.

By: Matt Mullenweg, John James Jacoby, Jennifer M. Dodd, in 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) in Simon Prosser.

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

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