Used by millions, Akismet is quite possibly the best way in the world to protect your blog from spam. It keeps your site protected even while you sleep. To get started: 1) Click the “Activate” link to the left of this description, 2) Sign up for an Akismet plan to get an API key, and 3) Go to your Akismet configuration page, and save your API key.
Version 3.2 | By Automattic
Category Tag Pages
Adds categories and tags functionality for your pages.
Version 1.0 | By Marzio Carro
Feed Them Social (Facebook, Instagram, Twitter, etc)
Create and display custom feeds for Facebook Groups, Facebook Pages, Facebook Events, Facebook Photos, Facebook Album Covers, Twitter, Instagram, Pinterest and more.
Version 2.0.9 | By SlickRemix
Jetpack by WordPress.com
Bring the power of the WordPress.com cloud to your self-hosted WordPress. Jetpack enables you to connect your blog to a WordPress.com account to use the powerful features normally only available to WordPress.com users.
Version 4.3.1 | By Automattic
List category posts
List Category Posts allows you to list posts by category in a post/page using the [catlist] shortcode. This shortcode accepts a category name or id, the order in which you want the posts to display, the number of posts to display and many more parameters. You can use as many times as needed with different arguments.
Version 0.70 | By Fernando Briano
Manage all your 301 redirects and monitor 404 errors
Version 2.4.5 | By John Godley
Assign tags to groups and display them in a tabbed tag cloud
Version 0.21.1 | By Christoph Amthor
WP Cleanup Optimizer Lite Edition
It allows you to optimize your WordPress database without phpMyAdmin.
Version 2.0.97 | By Tech Banker
WP Revisions Control
Control how many revisions are stored for each post type
Version 1.2.1 | By Erick Hitter
The first true all-in-one SEO solution for WordPress, including on-page content analysis, XML sitemaps and much more.
Version 3.6.1 | By Team Yoast