For those of you who are interested in developing your own investing screeners/apps, IEX provides a free web API service that allows you to pull real time US market data. I find this pretty cool! API docs can be found here.
And to give even more credit to these people, Brad Katsuyama is the guy who has fought HFT (High Frequency Trading) front-running practices, founding IEX as the result. Here’s a video of him talking about this. For more context, read Michael Lewis’ book, Flash Boys.