hexo-autonofollow
Adds nofollow attribute to all external links in your hexo posts automatically.
posthtml-external-link
Add 'rel="external noopener nofollow"' and 'target="_blank"' to all external links [PostHTML Plugin]
posthtml-link-noreferrer
This plugin add `rel="noopener"` and `rel="noreferrer"` to all links that contain the attribute `target="_blank"`.