You'll need to get a data feed provider that gets that info. I get it through EchoPro. www.echotradeonline.com I think you can from www.redi.com software and probably Bloomberg too.
http://www.nysedata.com/alerts - can get it directly from the exchange but of course not a valid option for retail other than that i know reuters carries is it and bloomberg publishes it as news. other than that i don't think you'll be able to get it and if you can i'd be interested also. there's also the NOII feed from NASDAQ. http://www.nasdaqtrader.com/trader/data/noii.stm found some retail places that have it but don't really allow for receiving all of it over an api
I never was able to find it as a retail trader. I don't know why. A lot of prop firms offer it though.
What prop firms offer market on close order imbalance information? Also, can you lookup market on close order imbalance information on bloomberg for specific stocks? For example can I lookup market on close order imbalance imformation on IBM?