I was doing a lot of work with AWS Lambda, which meant uploading big zip/JAR files to S3 semi-regularly. Each upload destroyed the place's upload bandwidth, rendering it unusable even for browsing.
This could be solved by using AWS Lambda Layers, or running my build process inside of AWS itself, but I'm stubborn and didn't want to change my process. :) So I whipped up a little tool that uses xdelta3 to send patches, which get reconstituted on the other end.
I've been using it for a while and love it, so I figured I'd polish it up and see if it's useful for anyone else. Happy to answer any questions about it, too!