Thank you, everyone, for your suggestions.

We reached out to some of the founders of Fotopedia and are reaching out to Fotopedia users via Fotopedia as well as Twitter.

We also wrote a blog post comparing some of the alternatives, which we hope people will find useful.

https://bonjourn.al/blog/17-fotopedia-alternatives-a-short-l...

I've also posted the same question on Quora:

https://www.quora.com/How-does-a-startup-take-advantage-of-a....

Thanks again!