"It's the same as a user deciding to make a backup of a webpage on their computer..."
... and then publishing it on the Internet.
(This is not meant to be snarky or to imply opposition to your product at all. I think there is a meaningful difference between saving to a computer and saving to a web-accessible, apparently globally readable website.
Isn't it a users responsibility to obey copyright restrictions in this case, given that we never publish content unless the user does it? It's basically the same situation as hosting a website, if you upload and publish a copyrighted page, is the host responsible?
In my opinion, those two cases are not similar. I doubt that this type of automatic caching/publishing would have any protection under the DMCA safe-harbor laws unless you're making it clear to users what they're doing (I'm not a user of the service, so maybe you already are).
If I understand correctly, the users of your site are simply bookmarking pages. You are then caching it, storing it, and publishing it with a world-readable URL. There are many ways that you could provide the same experience to the user without making the cached page publicly accessible.
If you were to give users the option to make specific bookmarks world-readable - and you provided a disclaimer explaining that they should not make copyrighted material world-readable - then it might be different. But that's probably something you should discuss with an attorney.
I wanted to let you know that I didn't mean to disappear without responding, but that sounddust expressed what I was thinking already so I don't have much to add. I did not know that the world-readable bit was opt-in; I think that's a good start, and I'm glad you're getting legal advice on this topic.
I am, I'm in the UK. I know the DMCA safe-harbor laws don't apply, but neither does the DMCA. Copyright law is similar everywhere, however, so I just wanted to get an idea. I have a lawyer researching this right now, though. Thanks again!
Your copyright law is similar to the US or Israel based one, not so strict as the main european one, which is based on the napolion code and is very very strict.
... and then publishing it on the Internet.
(This is not meant to be snarky or to imply opposition to your product at all. I think there is a meaningful difference between saving to a computer and saving to a web-accessible, apparently globally readable website.