I have an e-commerce site and I want to use imgur.com as a CDN for my product images by setting the image source of my image. I did not see anything in the ToS specifically about this. Can anyone offer any insight on this topic?
While Imgur is an image hosting service, their service is intended for the images to be commented upon, rated and shared within that site by members of their community.
Their TOS (under "Stuff not to do") does state "don't upload .. advertising (and) solicitations". Even if your e-commerce site doesn't sell products or services, the TOS also specifically states "Don’t hotlink to such content".
What you want to do, hosting the image on their site to be displayed on your site, that is called hotlinking. So, no, you would not be allowed to use imgur as a CDN.
It certainly used to be possible, indeed Stack Exchange themselves use Imgur for hosting all user uploaded images:
And some more recent comments on why they are still using Imgur over Amazon S3.
Note though that you will need a Pro account with them to ensure that your images persist.
However, this isn't really a CDN in the true meaning of the term: they aren't offering to serve images to users from servers near them (ie a server in Europe when the request comes from the UK) nor are they really promising specific up time or performance, the subscription just gets you more space for a longer period and bigger images. If that's all you are after then great, but it's not a CDN - from their Terms of Service (emphasis added):
Although of course we strive to make Imgur as dependable as possible, Imgur's services are provided on an AS IS – WITH ALL FAULTS basis. Your use of our service is entirely at your own risk. We do not guarantee the availability of our service at any given time, or the reliability of our service when it is running. We do not guarantee the integrity of, or the continued availability of, files on our servers. Whether we make backups, and if so, whether restoration of those backups will be available to you, is at our discretion.
Digging a bit deeper, I found this blog post on Imgur's technology stack where they say they've moved onto AWS to power most of the main site, and they also mention that they use a CDN for "direct image requests" - but the fact that they do use a CDN doesn't mitigate the overriding issues with the terms of service (or lack of there in).
It looks like they clarified their TOS to specifically shield them from being used as a CDN (emphasis mine):
Also, don't use Imgur to host image libraries you link to from elsewhere, content for your website, advertising, avatars, or anything else that turns us into your content delivery network. If you do – and we will be the judge – or if you do anything illegal, in addition to any other legal rights we may have, we will ban you along with the site you're hotlinking from, delete all your images, report you to the authorities if necessary, and prevent you from viewing any images hosted on Imgur.com. We mean it.
It is however not completely clear where the line is. To me, you can't upload images to imgur if they are meant to be used on your own website, but your users could still be uploading there if they want to share pictures (say, on your forums), as it looks like it is tolerated, and they even provide the BBcode for this. That's my understanding, at least.
Since their business model seems to be centered on people who visit their website, it seems understandable that they limit hotlinking as much as they can.