When hiring a freelancer, should I lump together related tasks or spread them out?

I'm building a web app that will require API integration with numerous platforms like Flickr, Tumblr, etc. It's relatively straight forward stuff--I just need to allow users to import their various subscriptions into my web app. But I'm literally planning to integrate with over a dozen APIs/platforms. Should I lump together these tasks as one big project (on a site like guru.com or freelancer.com) or should I divide each gig into chunks?

Once a developer has integrated one API with my app, it should be relatively easier to integrate additional APIs. But I'm afraid one big project will unreasonably drive up my costs.

What's the best way to go about this?

Put it all together for the purpose of finding someone. You don't want 12 different programmers working on your software, that would be a nightmare to manage and would require you to train 12 people.

As for actually doing the work once you find someone, break it down to small tasks and give them one at a time.

As for the price, I would find someone to work on an hourly rate instead of paying a fixed price if possible. That way you can always quit after one integration if you aren't happy with them and get someone else to continue on.

Why not define a single api and use a service like zapier for integration? Here is a list of products / services that can exchange info.

Depending on your product, this may open up additional channels.