Hi, I think I am the right person you are looking for!~
I have read all the requirements,you want a photo gallery that is auto generated from a directory. I am a very good jquery developer, i can develop customized plugin for you and directory in dropbox is not a problem.
I am very confident to take this project and complete in time with best quality.
So just give me a chance.
Here's my profile that you can check my previous jobs and my client's reviews on me:.
https://www.freelancer.com/users/2798015.html
Thank you!
Regards,
Bryant