Like most of the residents in her East Austin neighborhood, Charlotte Colis lost power and cell service last week as a result of a historic winter storm. When she arrived at her dad's place on Tuesday evening, she had access to both for the first time in two days and used it to check Facebook, where she found a flood of activity.

Colis is a co-administrator of the private Buy Nothing East Riverside-Oltorf/Montopolis group, one of 60 hyperlocal groups active in the Austin area. She quickly began responding to dozens of requests from Facebook users who wanted to join and reading posts from existing members, who had offered hot showers, phone charging, rides and food to people in need. "It was absolutely one of the best, most heartwarming things I've ever seen," she told Austonia.