guusifs

This plugin is intended to make on site SEO very simple, not necessarily easy. The basic idea is to add the meta description tag to your pages and posts.
Next to adding the meta description tag it also has the option to override the default title of your post and/or display clean titles without the site name.
More information about the background of the plugin in the IFS SEO Simple main screen. Just download and install. The plugin won’t change anything before you configure it, so you can install it safely. You will only see some additional fields in the edit screen, but if left empty they don’t do anything.

Plugin Name: IFS Seo Simple

Purpose of this plugin is to make on site search engine optimization simple.

I'm a Ninja

This interlinking plugin for WordPress will let you easily and meaningfully link to your old articles, pages or other sites to improve their rankings in search engines and generate more clicks.
The Internal Link Building plugin lets you assign keywords to given destination URLs. This way your website will link within itself like it’s done in Wikipedia – every time a keyword occurs, it links to the page you specified in the plugin dashboard.
You can: 
* set the words to be case sensitive (to only interlink your brand name for example), 
* make links nofollow (makes sense when you link to affiliate products), 
* upload keywords in bulk, etc
Note: Please do use the plugin in moderation to avoid over-optimization. Meaningful and user-friendly inter-linking goes a long way!
This plugin is supported by <a href="http://www.internetmarketingninjas.com/" rel="nofollow ugc">Internet Marketing Ninjas</a>.
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The settings page is under the Posts menu -> Keywords in 2.7+. It’s under Manage -> Keywords, in older versions of WP (up to 2.5 or 2.6) .
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This plugin allows you to mass-upload keywords. So you just need to prepare a CSV file in Excel and then copy-paste it into the mass-upload box in your admin panel and then click upload! This is great for larger sites targeting multiple keywords that want to speed things up.
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It’s up to you whether you make cAsE ReLeVaNT to your links. Check the “Exact Match” checkbox for it to only match when the case is the same as you typed the word into the admin panel. Leave it unchecked to have all cases link to your selected page.
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Post-level overrides of globally-assigned keywords.
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Link to sources or affiliate links whom you reference a lot.
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Build internal links automatically to pages you regularly reference.
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Make a link nofollow. For example, if you link to particular Wikipedia pages a lot then set the nofollow to be automatic.
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Link multiple keywords to a single URL. Target all a page’s keywords at once! Just put a space, a pipe (eg |) and a space between the multiple keywords. E.g. affiliate | affiliate marketing. More efficiency! More time savings!
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Pick the number of times a keyword will link to a particular URL. If you only want the words social media to link to your social media category once, you can do that. Notice that social gets linked next, since I also have that keyword assigned to link to the same page.
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Internal Link Building

line 706 of plugin is considered unsupported operator, didn't check the file itself, but going to leave this here for debug purpose.

not working since 4.7.3

This plugin will let you easily link to your old articles, pages or other sites to improve their rankings in search engines and generate more clicks.

Plugin Name: IFS Seo Simple vs Internal Link Building