I've been using Jack to manage & upload my app data to iTunes Connect for a while now. The really great thing is that you can select a bunch of screenshots from your desktop, drop them on to a language and it puts them in the right place for various iOS devices sizes for you. Plus when making changes to languages you don't have to wait for the page to load each time. All edits are done offline, then you click upload to send the changes to iTunes Connect.
Monster Mingle