Re-SRC is a tool that allows you to automatically serve responsive images for your website from their cloud servers. It delivers a new image file each time the browser window (viewport) is resized.

To use it in your HTML when linking to an image, you would do the following:

<img src="http://app.resrc.it//www.your-domain.com/img/img001.jpg"/>

Some more background for SEO considerations:

As an example, looking at their demo page's code, the src of the Arc de Triomphe photo — when the browser window is resized to be at a tablet-width — shows this particular file at it's widest. It is found under the following URL:


If the viewport is increased to desktop-width, then a smaller image is served in line with the design; see this URL:


If I change the viewport to be about half-way between those two, then the image's URL is:


In other words, I found that there is a separate file for every 10-pixel increment of the image width. Very cool for saving bandwidth on mobile devices and service responsive/retina images on others, but...

Here are two problems I see for SEO:

  1. The img on your site, part of your semantic markup, will not be hosted on your site at all, or even a server you control. Any links to these images will pass on "link juice" to Re-SRC's site instead.
  2. You are serving a vast array of different image files to different people — some may link to one, others to another size. Then there's the question of what different search engine crawlers will see.


  • There seems to be no fallback option if their servers are down.

Do you see any other concerns? Or, perhaps, do you not see those as concerns?

I also found out that when JavaScript is disabled (though search engines do crawl with JS in their inventory as well) — Re-SRC returns really pixelated images on it's demo page:

enter image description here

2 Answers 2


Hi Guys I actually work on ReSRC.it so I hope I can contribute wisely.

Thanks bybe for your accurate and insightful response.

With regards to the link juice I guess any juice would actually go to our app servers (app.resrc.it) rather than our actual website that sits on a different domain so we stand to gain nothing on that regard. Ultimately those images are linked from your site so it should be your site that the image links back to. I'm confident google are aware of the fact that people are starting to use CDNs more and more to host resources and hopefully these sites won't be discriminated against.

With regards to javascript being turned off and spider crawling; on our demos we've deliberately adopted a mobile first approach which uses a highly optimised image which is then swapped out by a higher quality / pixel perfect version. You can however easily set that initial image size and quality using our parameters in the image path. e.g. /s=w960/o=85/http://www.resrc.it/img/demo/demo-image-11.jpg would produce an initial image of 960px at 85% quality. This would mean google image results would have a decent quality version in their index.

Hope this contributes.



  • Good to hear from you folks! It's a great idea and you've done a lot of good work. It seems that there's a trade-off between a mobile first approach and SEO for Google Image Search - both of which are important to me. In fact, I wouldn't be considering a tool like Re-SRC without mobile first. I wonder if Google "gets it" and canonicalizes the highest quality version - maybe this can be helped along with RFDa/microdata?
    – Baumr
    Commented Jan 12, 2013 at 2:26

The SEO problems you've raised are the same as any other cloud apart from the viewpoint changes in the image URLS which is new and I'm very interested in.

  1. While linking images does help site trust and passes a little amount of juice since img tags you can't use nofollow and any site embedding your images will pass the juice. With this said its considered a TINY amount of juice and most consider it worthless. However! it does help your linking DIVERSITY. Generally as a golden rule it's best to have all types of links going to your sites href image links, text links, anchor links, nofollow and do follow on all types of platforms such as forums, blogs, social media etc etc. You could always use a few pictures on the site that are not on the cloud and link to via profile avatars and so forth to increase your linking Diversity.

  2. Google will only index pictures that can be found on a page, since this platform uses viewpoint and javascript to switch between different images your find that only the default image will be indexed by Google.

For example when disabling JS the following image became the master and the URL did not change. Since Google doesn't use Javascript when crawling this is the image it will find and use, and the Google image engine is good at picking out files that are the same but different sizes 'GENERALLY'.



The Benefits of using a cloud out weighs that of worrying about image linking and so on also since more and more people are moving to such CDN networks it could well be that Google rewards the domain who first links to image for all we know - passing the juice along. I'm pretty sure that or in future Google will take this into account and pass accord-ling.

Furthermore, Google loves rich content as you know and that includes things like media files such as videos and images - Google rewards for putting images and videos on the page and since this passes content value I'm pretty sure they can pass on juice if the image is unqinely found on the domain in question. Ofc this is pure speculation but it would make sense.

Personally I wouldn't worry about the SEO too much and focus on delivering fast rich content. Best SEO is providing for your visitors at the best possible experience within Reason and this is a good reason - Speed Matters ;)

  • 1
    Good answer overall, but regarding: Since Google doesn't use Javascript when crawling... --I don't believe that's actually true anymore. Commented Dec 24, 2012 at 14:31
  • 1
    Google understands most javascript. Google does not use your sites Javascripts when viewing any sites as a normal browser would and the OP of this thread knows that hence he made the question. Google crawls your Javascript and tries to make sense of it, and no point does it actually execute it (HENCE DOES NOT USE). And at no point was this suggested otherwise. Commented Dec 24, 2012 at 21:22
  • +1, and I agree that it's a good overall post. I think your first statement would need a source, no?
    – Baumr
    Commented Dec 28, 2012 at 20:51
  • Well I know that Google insight is now checking to see if pictures can be served up in lower formats developers.google.com/speed/pagespeed/insights I might be wrong but paste in the URL and see what it says. On my responsive it said the picture was larger and should be served smaller for devices. Commented Dec 30, 2012 at 23:15
  • @bybe, the link you gave is not what I see when JavaScript is turned off. What I see is a really pixelated and otherwise low-quality image — if this was what'd appear in Google Image search and would be indexed as the canonical, then it's a big problem.
    – Baumr
    Commented Jan 5, 2013 at 22:15

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