Hi, I would recommend looking at Talend Open Studio (TOS) Probably the JSON components will not be enough but they could easily be extended.
I suggest opening a question in TOS forum about having this support. If anyone decides to do so I would appreciate replying back with the link to the post either to the mailing list or my gmail address. I know I will be jumping into the same question soon once our product starts producing. Thanks! -Nestor
