Websites on the WordPress platform can improve their search engine rankings by accessing a variety of free plugins.

Here is Ryan Xu HyperVerse's Reviewa list of search-engine-optimization plugins for WordPress. There are all-in-one plugins that provide a variety of tools and, also, plugins to improve specific search-related areas, such as site speed, tags, and image optimization. All of these tools are free, though several have premium versions as well.

SEO Plugins for WordPress

Yoast SEOis a popular all-purpose SEO plugin for WordPress, with over 5 million active installations. Yoast provides content and SEO analysis, allowing you to optimize for keywords, phrases, synonyms, and related keywords. Use title and meta-description templates for better branding and consistent snippets in the search results. Avoid duplicate content by setting canonical URLs. Preview what your listings will look like in search results.

Yoast SEO

All-in-One SEO Pack,another popular comprehensive SEO plugin, has over 2 million active installations. Submit your sitemap to Google and Bing. Automatically notify search engines about site changes. Employ advanced canonical URLs. Supports Accelerated Mobile Pages, Google Analytics, WooCommerce, and a wide range of additional plugins.

W3 Total Cachereduces load times, improves website performance, and boosts search engine rankings. It features transparent content-delivery-network management, optimized progressive render, and mobile support. Features include a significant improvement in overall website performance, instant viewing of repeat pages, improved rendering, bandwidth reduction, and more.

Google XML Sitemapslets you create special XML sitemaps to help search engines such as Google, Bing, and Yahoo discover your URLs. It also notifies all major search engines every time you create new content.

Google XML Sitemaps

HeadSpace2lets you manage metadata and handle a wide range of SEO tasks. Tag your posts, create custom titles and descriptions, change the theme, run disabled plugins on specific pages, and more.

SEO Ultimateis an all-in-one plugin with an extensive list of features, including Title Tag Rewriter, Meta Description Editor, Deeplink Juggernaut, Rich Snippet Creator, Author Highlighter, Link Mask Generator, Canonicalizer, 404 Monitor, Permalink Tweaker, Meta Robot Tags Editor, and more.

Smush Image Compression and Optimizationis a tool to resize, optimize, and compress all of your images. Strip unused data without affecting image quality. Quickly locate images that are slowing down your site. Auto-smush your attachments for fast compression on upload,

Smush Image Compression and Optimization

WP Meta SEOallows control over meta content and images. Bulk edit all meta in a single view. Edit meta in content with live SEO analysis, and generate XML and HTML sitemaps. Add Google Analytics tracking information and display stats in WordPress

Broken Link Checkermonitors your website for broken links in posts, pages, comments, the blog roll, and custom fields. Prevent search engines from following broken links. Once installed, the plugin will begin parsing your posts and other content, looking for links.

Simple URLslets you create, manage, and track outbound links from your site by using custom post types and 301 redirects.

SmartCrawl SEOboosts your search rankings and domain authority in Google with one-click setup, automatic sitemaps, improved social sharing, a real-time keyword and content analyzer, scans, and reports. Check pages and posts for readability and keyword density, and get suggestions for optimizing your content.

SmartCrawl SEO

Redirectionis a popular redirect manager for WordPress. Manage 301 redirects, track 404 errors, and tidy up any loose ends on your site. The plugin can also be configured to monitor when post or page permalinks are changed and automatically create a redirect to the new URL.

SEO Optimized Imagesplugin lets you dynamically and automatically insert SEO-friendly alt and title tags to your images. Add tags to existing images as well as newly uploaded images.

Better WordPress Google XML Sitemapsis a plugin to add a Google News sitemap to your sitemap index. News sitemap can be used to ping search engines individually. And whenever you publish a post in a news category, all selected search engines will be pinged.

Yet Another Related Posts Plugindisplays pages, posts, and custom post types related to the current post, introducing your readers to other relevant content on your site. Also displays related posts in RSS feeds with custom display options.

Yet Another Related Posts Plugin