I've tried Riak CS and Walrus, and read a few other's documentation pages but can't tell whether they would support this or not.
What I have is an application that uses S3 policies to allow the client to upload and download directly from their browser. I'm looking for a way to replace S3 (for some customers, who would prefer their data not in Amazon's cloud), without having to maintain two different branches of code everywhere I currently talk to S3.
Example of what I do now: https://aws.amazon.com/articles/1434
Help would be greatly appreciated, I'm stumped!