It can certainly be be done with code but I don't have any to give you. The idea is to iterate through the repeating section, decoding each Base64 value into its bytes, and then send each of these to the destination location via a PUT request.
I can assure you that the highly tested, highly reliable code in qRules will save you time and money in the long run, and strongly suggest that option. It has a trial version, so you can try before you buy, to see how easy it is.