Tran Ngoc Tuan Anh

This plugin adds rel=”nofollow” to all external links in post content. So, your flow of PageRank can not run to other websites and your blog’s SEO is improved.
The internal links are unchanged.
Requires PHP5.

External Nofollow

Pawel Cmachowski

Plugin is extension for WooCommerce plugin.
Plugin allows you to create multiple External / Affiliate product URLs and buttons text.
Plugin creates extra fields on External / Affiliate product edit form, with repeater of multiple external URLs. 
Also, plugin gives you ability to open external / affiliate URLs on new window.
Features:
<ul>
<li>Ability to create multiple buttons with external / affiliate URLs</li>
<li>Ability to open external / affiliate URLs in new window – configuration per product</li>
<li>Ability to display additional external / affiliate URLs on shop/category page – configuration per product</li>
<li>Ability to change additional button templates by hooks – <code>mepu_woo_product_page_template</code> and <code>mepu_woo_shop_page_template</code></li>
</ul>

Multiple external product URLs for WooCommerce

Thanks

Plugins gives you ability to add multiple external product URLs on WooCommerce product edit page.

External Nofollow vs Multiple external product URLs for WooCommerce