Certain CMS' running on IIS like Sitecore do not give image files appropriate file formats like .png or .jpg by default, but instead link to images as:

<img src="/media/Some Folder/EX-IMG.ashx" alt="Example" />

Ignoring the spaces, non-descriptive filename, and capitals (likely to break and/or cause duplicate content issues), does that URI with .ashx pose a problem?

Is using the correct image file format a ranking factor in organic search for the page that the image appears on, or is having a decent alt attribute enough?

(Note, it is not necessary to have this image rank in Google Images, but inform spiders that it is relevant and contextual media related to the text content on the page.)

2 Answers 2


To answer your question: no, it should not pose a problem for SEO.

Why not - given that ashx has nothing to do with images, you ask? Because of the MIME type being sent with the file header.

The .png file ending is actually not what determine what the browser has to interpret, but rather the file headers of the HTTP request. The file headers sent when the browser is requesting an image file of type .png from the CMS, contain the MIME type media/png and the .ashx extension is thus, irrelevant. Same goes for HTML files - they can be called .baumr, as long as the MIME type is text/html. This can easily be set up in both Apache and IIS.

The URL example you have used, is not too common. As you mentioned, in a good setup it should be descriptive, solely for SEO/Image search purposes: /images.ashx?id=picture-of-an-elf

  • 1
    Yeah, non-standard image extensions are fine. Jun 2, 2013 at 20:03
  • 1
    Better yet, use no extensions at all :) /images?id=picture-of-an-elf or /images/picture-of-an-elf (which runs index.ashx and passes in picture-of-an-elf) That way you can change your technology without having an identity crisis with your URLs! Jul 9, 2013 at 13:40

Regardless of the "type of" file requested from the server (as would seem to be suggested by the file ".ashx" extension) , the image file format (and corresponding mime-type) received to the client must still be one of png, jpg, gif etc. as otherwise the browser / user-agent will not render/understand it.

So, I don't see how this would affect Google Search.

However, it could affect Image Search for the reasons you mention... none descriptive filename etc. But if the indexing of images is not a concern (and these are perhaps blocked from Googlebot-Image anyway) then I can't see that it is a problem.

...but inform spiders that it is relevant and contextual media related to the text content on the page.

Does Google look at the type/context of the images themselves when determining rank in Google Search?

  • Yes, images enhance on-page SEO — based on alt attribute, contextual placement, filename, etc.
    – Baumr
    May 24, 2013 at 12:17
  • Actually, modern browsers render .ashx files as images without any problems (see image from Sitecore's official site)
    – Baumr
    May 24, 2013 at 12:18
  • Yes, the alt text etc. certainly helps SEO, but the image itself? That image you link to is served as an ordinary PNG image.
    – MrWhite
    May 24, 2013 at 12:25
  • Not sure what you're trying to say with the 1st part, perhaps you misunderstood? Anyway, the latter part of the image's filename is carnival%20cruise%20homepage%20img.ashx, and if you try an image like this, this or this and download it — it'll still be .ashx
    – Baumr
    May 24, 2013 at 12:34
  • The first part... of my answer or the comment? The URL (or filename) that you quote, ending in .ashx is the URL of the resource requested from the server. This itself does not necessarily indicate the format of the file returned (there is no such thing as an ashx image file format) - if that is what you are implying? The last 3 images you link to are all jpegs, and this is indicated to the browser/spider by the Content-Type: image/jpeg HTTP response header. The mime-type is what indicates the type of the file and this is what the browser sees.
    – MrWhite
    May 24, 2013 at 15:01

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