Moz Q&A is closed.
After more than 13 years, and tens of thousands of questions, Moz Q&A closed on 12th December 2024. Whilst we’re not completely removing the content - many posts will still be possible to view - we have locked both new posts and new replies. More details here.
How important is the file extension in the URL for images?
-
I know that descriptive image file names are important for SEO. But how important is it to include .png, .jpg, .gif (or whatever file extension) in the url path? i.e. https://example.com/images/golden-retriever vs. https://example.com/images/golden-retriever.jpg
Furthermore, since you can set the filename in the Content-Disposition response header, is there any need to include the descriptive filename in the URL path?
Since I'm pulling most of our images from a database, it'd be much simpler to not care about simulating a filename, and just reference an image id in my templates.
Example:
1. Browser requests GET /images/123456
2. Server responds with image setting both Content-Disposition, and Link (canonical) headersContent-Disposition: inline; filename="golden-retriever"
Link: <https: 123456="" example.com="" images="">; rel="canonical"</https:> -
In theory, there should be no difference - the canonical header should mean that Google treats the inclusion of /images/123456 as exactly the same as including /images/golden-retriever.
It is slightly messier so I think that if it was easy, I'd go down the route of only ever using the /golden-retriever version - but if that's difficult, this is theoretically the same so should be fine.
-
@Will Thank you so much for this response. Very helpful.
"If you can't always refer to the image by its keyword-rich filename"...
If I'm already including the canonical link header on the image, and am able to serve from both /images/123456 and /images/golden-retriever (canonical), is there any benefit to referencing the canonical over the other in my image tags?
-
Hi James. I've responded with what I believe is a correct answer to MarathonRunner's question. There are a few inaccuracies in your responses to this thread - as pointed out by others below - please can you target your future responses to areas where you are confident that you are correct and helpful? Many thanks.
-
@MarathonRunner - you are correct in your inline responses - it's totally valid to serve an image (or other filetype) without an extension, with its type identified by the Content-Type. Sorry that you've had a less-than-helpful experience here so far.
To answer your original questions:
- From an SEO perspective, there is no need that I know of for your images to have a file extension - the content type should be fine
- However - I have no reason to think that a filename in the Content-Disposition header will be recognised as a ranking signal - what you are describing is a rare use-case and I haven't seen any evidence that it would be recognised by the search engines as being the "real" filename
If you can't always refer to the image by its keyword-rich filename, then could you:
- Serve it as you propose (though without the Content-Disposition filename)
- Serve a rel="canonical" link to a keyword-rich filename (https://example.com/images/golden-retriever in your example)
- Also serve the image on that URL
This only helps if you are able to serve the image on the /images/golden-retriever path, but need to have it available at /images/123456 for inclusion in your own HTML templates.
I hope that helps.
-
If you really did your research you would have noticed the header image is not using an extension.
-
Again, you're mistaken. The Content-Type response header tells the browser what type of file the resource is (mime type). This is _completely different _from the file extension in URL paths.
In fact, on the web all the file extensions are faked through the URL path. For example, this page's URL path is:
https://moz.com/community/q/how-important-is-the-file-extension-in-the-url-for-images
It's not
https://moz.com/community/q/how-important-is-the-file-extension-in-the-url-for-images.html
How does the browser know the the page is an html doc? Because of the Content-Type response header. The faked "extension" in the URL path, is unnecessary.
You can view http response headers for any URL using this tool.
-
-
Do you need a new keyboard?
-
@James Wolff: I'm really hoping you're being sarcastic here. As it's totally fine to serve it without the extension. There are many more ways for a crawler to understand what type a file is. Including what @MarathonRunner is talking about here.
-
This isn't accurate. File extension (in the url path) is not the same as the **Content-Type **response header. Browsers respect the response header Content-Type over whatever extension I use in the path.
Example: try serving a file /golden-retriever.png with a content type of image/jpeg. Your browser will understand the file as a .jpg. If you attempt to save, your browser will correct to golden-retriever.jpg.
You can route URLs however you want.
Additionally, I'm not aware of any way browsers "leverage cache by content type". Browsers handle cache by the etag/expires header.
Got a burning SEO question?
Subscribe to Moz Pro to gain full access to Q&A, answer questions, and ask your own.
Browse Questions
Explore more categories
-
Moz Tools
Chat with the community about the Moz tools.
-
SEO Tactics
Discuss the SEO process with fellow marketers
-
Community
Discuss industry events, jobs, and news!
-
Digital Marketing
Chat about tactics outside of SEO
-
Research & Trends
Dive into research and trends in the search industry.
-
Support
Connect on product support and feature requests.
Related Questions
-
Image Audit: Getting a list of *ALL* Images on a Site?
Hello! We are doing an image optimization audit, and are therefore trying to find a way to get a list of all images on a site. Screaming Frog seems like a great place to start (as per this helpful article: https://moz.com/ugc/how-to-perform-an-image-optimization-audit), but unfortunately, it doesn't include images in CSS. 😞 Does the community have any ideas for how we try to otherwise get list of images? Thanks in advance for any tips/advice.
Intermediate & Advanced SEO | | mirabile0 -
Switching from Http to Https, but what about images and image link juice?
Hi Ya'll. I'm transitioning our http version website to https. Important question: Do images have to have 301 redirects? If so, how and where? Please send me a link or explain best practices. Best, Shawn
Intermediate & Advanced SEO | | Shawn1241 -
Duplicate URLs ending with #!
Hi guys, Does anyone know why a site can contain duplicate URLs ending with hastag & exclamation mark e.g. https://site.com.au/#! We are finding a lot of these URLs (as duplicates) and i was wondering what they are from developer standpoint? And do you think it's worth the time and effort adding a rel canonical tag or 301 to these URLs eventhough they're not getting indexed by Google? Cheers, Chris
Intermediate & Advanced SEO | | jayoliverwright0 -
Would changing the file name of an image (not the alt attribute) have an effect of on seo / ranking of that image and thus the site?
Would changing the file name of image, not the alt attribute nor the image itself (so it would be exactly the same but just a name change) have any effect on : a) A sites seo ranking b) the individual images seo ranking (although i guess if b) would be true it would have an effect on a) although potentially small.) This is the sort of change i would be thinking of making :  changed to 
Intermediate & Advanced SEO | | Sam-P0 -
Does Google Read URL's if they include a # tag? Re: SEO Value of Clean Url's
An ECWID rep stated in regards to an inquiry about how the ECWID url's are not customizable, that "an important thing is that it doesn't matter what these URLs look like, because search engines don't read anything after that # in URLs. " Example http://www.runningboards4less.com/general-motors#!/Classic-Pro-Series-Extruded-2/p/28043025/category=6593891 Basically all of this: #!/Classic-Pro-Series-Extruded-2/p/28043025/category=6593891 That is a snippet out of a conversation where ECWID said that dirty urls don't matter beyond a hashtag... Is that true? I haven't found any rule that Google or other search engines (Google is really the most important) don't index, read, or place value on the part of the url after a # tag.
Intermediate & Advanced SEO | | Atlanta-SMO0 -
Is there a limit to images file names?
Hi, I have an eCommerce site with hundreds of product images. For management reasons files are named in length to have the product details in them.
Intermediate & Advanced SEO | | BeytzNet
Is there a limit for a filename length before it is considered ambiguous or spammy etc.?
(it usually ranges 50-70 chars). Thanks0 -
Number of images on Google?
Hello here, In the past I was able to find out pretty easily how many images from my website are indexed by Google and inside the Google image search index. But as today looks like Google is not giving you any numbers, it just lists the indexed images. I use the advanced image search, by defining my domain name for the "site or domain" field: http://www.google.com/advanced_image_search and then Google returns all the images coming from my website. Is there any way to know the actual number of images indexed? Any ideas are very welcome! Thank you in advance.
Intermediate & Advanced SEO | | fablau1 -
Strange URLs, how do I fix this?
I've just check Majestic and have seen around 50 links coming from one of my other sites. The links all look like this: http://www.dwww.mysite.com
Intermediate & Advanced SEO | | JohnPeters
http://www.eee.mysite.com
http://www.w.mysite.com The site these links are coming from is a html site. Any ideas whats going on or a way to get rid of these urls? When I visit the strange URLs such as http://www.dwww.mysite.com, it shows the home page of http://www.mysite.com. Is there a way to redirect anything like this back to the home page?0