Here are the best WordPress plugins that will add new functionality to your WordPress websites that is otherwise not available in the vanilla version of WordPress software. These are all free and open-source plugins and you can download them from the official WordPress plugins repository.

The Best WordPress Plugins (Updated)

1. Search Regex – This adds extremely powerful search and replace capabilities to your blog. You can find and replace almost any kind of data stored on your WordPress site including post titles, excerpts, comments, and meta data. It even supports regular expressions.
2. Redirection – If the URL of an existing post has changed or if an external site is linking to a non-existent page on my site, I can create redirection rules and automatically forward all the incoming traffic to the right pages. Simple 301 is also a good alternative.
3. Yoast SEO – This is probably the only SEO plugin you need for your WordPress blog. It helps you create better titles, you can block duplicate pages (like archive pages) from search bots, and it also adds the necessary meta tags required for more search-friendly Google snippets. The new releases also integrate Twitter Title Tags and Facebook Open Graph tags.
4. W3 Total Cache – This is possibly the best caching plug-in for WordPress and it will definitely help improve your site’s page speed score. I was previously using Hyper Cache but W3 Total Cache does much more - it lets you minify scripts, cache database queries, add expiry headers to static images and more.
5. 404 Email Notifier – This sends you an email notification as soon as a visitor lands on a 404 page on your WordPress website. The email messages have details about the visitor’s IP address, what browser they are using and the referral URL that led him to that broken link.
6. SlideShare – This helps you easily embed SlideShare presentations in blog posts with the help of short codes – see samples. Update: This maybe optional as WordPress core itself supports SlideShare embeds through oEmbed.
7. Smart YouTube – This lets you embed YouTube videos in blog posts using standing video URLs and the embedded player can be customized. It adds a thumbnail of the embedded video in the RSS feed and the same plug-in can also be used to embed videos from Facebook and Vimeo.
8. YARRP – The related posts plug-in adds links to old stories that may be contextually related to the content of the current article. It also helps expose your archived content to search bots.
9. WP Optimize – Use the WP Optimize plugin to clean-up your WordPress database tables. It can remove post revisions, trash spam comments and also optimize your MySQL tables so that it works more efficiently and also consumes less space.
10. Adminer - This will help you manage your MySQL databases from the WordPress dashboard itself. You can run SQL queries, browse tables or perform database optimization. Less complicated than phpMyAdmin.
11. Authenticator - Enable 2-step authentication for your WordPress blog, similar to Dropbox or your Gmail account. Authy is also a good alternative for enabling 2-factor authentication in WordPress.
12. WP-DBManager – This plugin will help you backup your WordPress database manually or you can set up a scheduled job for automatic backup and the database files will be sent to your email address at set intervals. Advanced users can use WP-DBManager to run SQL queries against their WordPress database without the phpMyAdmin tool. There are other plugins that can save backups to Amazon S3 and Dropbox.
13. Debug Queries – Is your blog slow? Use the Debug Queries plugin plugin to determine which MySQL queries are taking more time to execute and thus slowing down the blog. Debug Bar is another related plugin org that shows PHP warnings, queries and other helpful debugging information in the WordPress admin bar.
14. P3 Profiler - Use the profiler plugin to figure out which WordPress plugins are slowing down yor website. It generates a pie chart detailing the time it takes to run each plugin while loading the various pages of your site.
15. Auto Post Thumbnail – WordPress added support for Post Thumbnail Images in WordPress 2.9 but if you have been using WordPress for long, thumbnails may not be associated with your old posts. Use the Auto Post thumbnail plugin to automatically generate thumbnails for such posts using the first image found in the post content.
16. Regenerate Thumbnails – When you change the default size (height and width) of post thumbnails (or featured images) on your blog, you can use this plugin to regenerate thumbnails with the new dimensions.
17. Google XML Sitemaps – Since you want Google and other search engines to know about each and every page of your WordPress website, you need an XML sitemap and this plug-in lets you generate one in a click.
18. XML Video Sitemap - The plugin generates an XML Sitemap for your WordPress blog with all the YouTube videos that are embedded in your blog posts. I am also using XML Sitemap for Images and XML Sitemap for Mobile.
19. Date in a Nice Tone - This plugin offers an alternate way to display dates in your blog posts. It displays the amount of time – like “a few days ago,” or “in the last month,” or “over a year ago” - that has passed since a post or page was published.
20. SyntaxHighlighter Evolved – If you regularly embed code snippets in your WordPress blog posts, this plugin will help you highlight the syntax of the source code in different colors for more comfortable reading. Supports all popular programming languages.
21. Pubsubhubbub – This will help you beat content scrapers using Fat Pings. When you publish a blog post, it will instantly ping Google and that is a strong signal to the search engine that you are the original author.
22. Bing 404 – If someone lands on a 404 page for which redirection is not yet enabled, this plug-in will display links to relevant article on the error page. For example, a 404 page like labnol.org/googledocs will have links to my Google Docs articles.
23. WP-Associatizer - This plug-in will automatically rewrite any Amazon URLs in your posts to use your Amazon Associates ID.
24. Template Tag SC – WordPress offers numerous template tags – like wp_list_pages() or wp_tag_cloud() – that you can use in your theme files. The plugin will help you insert the sam template tags directly in your blog posts or pages using Short Codes.
25. Limit Login Attempts - It logs the IP address and the exact date & time when a user is trying to log into your WordPress and also keeps track of unsuccessful login attempts. You can automatically lock out users after they have made ‘n’ unsuccessful login attempts.
26. CF Shortcode – This helps you insert custom fields inside your WordPress posts using the visual editor. This comes extremely handy when you want to add custom JavaScript inside your WordPress posts.
27. Advanced Excerpt – The post excerpts in WordPress are fixed at 55 words and often displayed with […] ellipsis at the end. This plugin lets you to specify a custom length of excerpts, you can get rid of the ellipsis and the excerpts can be configured to have full sentences so that there are no weird cuts.
28. Threat Scan - If you are every notic any suspicious activity on your WordPress site, use the Threat Scan plugin to automatically scan your PHP files and your WordPress databse for any malicious code that may have been injected through the backdoor.
29. Nice Search - This creates neat permalinks for your WordPress search pages. For instance, /?s=wordpress%20plugins will be redirected to /search/wordpress+plugins.
30. AssetsMinify - Google’s Page Speed guidelines suggest that the best way to make your web page more responsive is to minimize the number of files that must be downloaded when the page is loaded. You can use the Minify plugin to combine and compress all the JavaScript and CSS files and make your website faster.
31. Options Optimizer - As you install plugins, new entries are added to the wp_options table. When plugins are uninstalled they are supposed to clean up their options but some may skip that part eating memory. The Optimizer plugin will help you get rid of these orphaned entries.
32. File Monitor - The plugin will monitor your WordPress installation folder and will send email alerts when any file is added, deleted or modified on your server. Use this with Senitel for complete peace of mind.
33. Quick AdSense - While the title is AdSense, this plugin can be used to insert JavaScript based ads from any network anywhere on your blog pages including middle of the content. This can also be used for serving responsive Google Ads.
34. CodePress Admin - The Posts screen inside your WordPress dashboard display the post name, category, tags but with CodePress, you can add new columns to the view displaying meta data associated with the posts. For instance, you may show featured images next to the post title or even the value of a particular custom field.
35. Site Moni toring with Google Docs - This isn’t a WordPress plugin but should be a part of your WordPress arsenal. When the site goes down, you will get an instant email notification and an SMS alert through Google Docs.

Related reading: Improve WordPress Security with Plugins