When it comes to money, the best of intentions are often no match for biases, irrationalities and bad habits that can lead to buying too much, buying too high, or selling too low.

To help investors fight bad financial habits, companies are layering insights from behavioral finance -- the study of how psychology affects economic decisions -- into smartphone apps and online investing sites. They’re consulting with academic economists and psychologists, while also using rigorous testing and creative design to make sure their ideas work in the real world. 

Here’s a look at these start-ups’ attempts to alert, nudge and, well, manipulate people into becoming better savers, spenders and investors.