What happens when tech firms end up at the center of racism scandals?

Nextdoor's push to combat racial profiling is latest controversy when tech firms find themselves in scandals at intersection of race, social justice and free speech

The racist posts on Nextdoor.com became so frequent that they started to make Shikira Porter feel physically ill.

Billed as a "private social network for your neighborhood", Nextdoor allows users to write public messages to neighbors who have joined the site, which now has more than 110,000 local groups across the US. After Porter, who is black, signed up in her Oakland, California, neighborhood in 2013, she quickly discovered that many of her white neighbors were posting "crime and safety" alerts about "suspicious" people of color.