Pedram Cheraghi

AutoLink Keywords helps you easily add internal or external links to your content by automatically linking specified keywords.
Features: 
* Define keyword-URL pairs in the settings page. 
* Limit the maximum number of links per post. 
* Optionally open links in a new tab. 
* Optionally add rel=”nofollow” attribute. 
* Case-insensitive matching. 
* Prevents linking inside already linked text. 
* Lightweight and simple to use.
<h3>A brief Markdown Example</h3>
Define keyword-URL pairs like:
wordpress|https://wordpress.org 
php|https://www.php.net
Links will open in a new tab with optional nofollow attribute if configured.

AutoLink Keywords

Automatically links predefined keywords in your posts and pages to specified URLs.

mohsenshahbazi

Automatically link specified keywords to specified urls on post content . the linking changed made forever on post content . also you can define limit of keywords linked on post content to prevent google link spam trap 
Please feel free to offer any feature suggestions you might have and I will consider them for future releases.

WP KeyLink

Automatically link specified keywords to specified urls on post content . the linking changed made forever on post content .

AutoLink Keywords vs WP KeyLink