Does adding external images or javascript to a website affect its SEO?

Question

When adding images to your site, is it bad to use an image located on another site:

<img src='http://www.some_other_site.com/image.jpg'>

The same goes for javascript, is it bad to link to javascript located somewhere else:

<script type='text/javascript' src='http://www.some_other_site.com/js.js'></script>

I ask this purely from an SEO perspective (I am aware that if the other site takes down their image, or something happens to their server, that will affect the content on my site). I am especially curious about javascript, since it is actually common practice to link to javascript libraries on other sites.

Answer 1

In general, no it does not affect your SEO. However there are some issues you should be aware of:

• The external site could be quite slow, which could have a tiny impact on SEO as Google's algorithm includes site speed. However if you are wondering about things like Google hosting jQuery then they will almost certainly be faster than your own site, actually improving SEO.

• Hotlinking another image could increase that image's ranking in image search. This is unlikely to affect you directly unless they are a competitor and you want to always rank above them.

• The image or script could be removed from the other site like you said.

• The site could change the file if hotlinking is detected. For images they could refuse to serve it or even display something offensive.

• For scripts there could be security issues introduced if the site is a little untoward. They can run any JavaScript on your site, so could steal user information etc.

Note that most of the above only applies if you are hotlinking things without permission. Scripts like jQuery on Google's CDN are intended to be hotlinked.