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):
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).