Back in the day, not even that long ago really, people would trade services with each other.

Simbi is an online network where people can offer their skills and services--professional or otherwise--in exchange for other users’ services. It's a cashless marketplace hoping to tap into human potential with help from Y Combinator.

A group of founders who pitched at the first of two Y Combinator Summer 2016 Demo Days on Monday, however, are tackling issues faced by populations that have been largely left behind by the recent tech boom.