Nextdoor, launched in 2011, has always been defined by a user’s identity and location. To sign up for a Nextdoor account in the U.S., users must verify that they have a physical address located within one of the over 202,000 chunks of land that have been designated as a “neighborhoods.” Once verified, users have access to a private forum populated by others living within the same designation.

In some ways, the site’s design is directly inverse to the historically open and geographically unbounded nature of the internet. “Unlike most social media, Nextdoor’s premise is on limiting, rather than expanding, a prospective social network,” says Katie Lambright, a PhD candidate in history at the University of Minnesota and author of the paper “Digital Redlining: The Nextdoor App and the Neighborhood of Make-Believe.” “This manifests in some seemingly innocuous quaintness — going by first name, ‘thanking’ in lieu of liking — but the exclusivity simultaneously fosters discriminatory practices that are baked into the very structure of the app. It’s like a gated internet community.” That sentiment is central to Nextdoor’s manifesto, which reads, “We are simply you and your neighbors, together.”

“Nextdoor’s premise is on limiting, rather than expanding, a prospective social network.”

The site’s geographic specificity and real name policies makes Nextdoor a uniquely powerful resource for law enforcement. The platform has partnered with “over 3,500 public agencies across the country — including police, fire, city, and emergency management departments,” creating a direct line of communication between Nextdoor and these government agencies. The header photo on Nextdoor’s News section features its employees smiling next to police officers. “We believe technology is a powerful tool for making neighborhoods stronger, safer places to call home,” reads the platform’s manifesto. “We’re for neighborhood watch.”

Neighborhood watch groups, in their current definition, have existed in the U.S. since around the late 1960s. In 1972, the National Sheriffs Association created the Neighborhood Watch Program, unofficially deputizing property owners to keep “extra eyes and ears” on their streets. Sometimes, these groups have transcended their surveillance mandates and veered toward discrimination. That can include discrimination based on appearance, and skin tone.

“We can’t forget Trayvon Martin was killed by someone who was a part of a neighborhood group,” says Rahim Kurwa, assistant professor of sociology at the University of Illinois at Chicago. Kurwa examined Nextdoor in the journal Surveillance and Society, concluding that it’s become “an important platform” for policing race-based boundaries in residential spaces. “Neighborhood watch groups have been used as a tool to regulate race,” he says, “and these are digital versions of that.”

In 2015, Nextdoor was heavily criticized for the role it played in fomenting racial profiling on the platform. The company ultimately responded by tweaking its algorithm, adding occasional reminders to avoid racial stereotyping, and requiring users to add multiple other descriptors if they mention race. They said those moves cut down on “problematic posts” by 75%. (Since Nextdoor doesn’t allow open access to its information, there’s no real way to verify these claims, but the company did share their methodology with the news site Splinter in 2016; Nextdoor did not respond to multiple requests by OneZero for comment.)

But discrimination can come in forms other than those based on visual indiciators like skin tone or gender appearance. It can also hinge on the question of wealth and belonging. As the number of homeless people in U.S. cities continues to rise, Nextdoor’s definition of who constitutes a member of neighborhood — namely only those individuals with physical addresses — isn’t matching the reality on the ground. And activists say the exclusion of these populations from official “neighborhoods” further dehumanizes the homeless.

In August, an encampment in the Eagle Rock neighborhood of Los Angeles was purposely set on fire.

“Nextdoor is incomplete,” Kurwa says. “If you’re homeless, even though you might be within this geographic boundary, you effectively don’t have citizenship on the platform.”

In 2016, Mike Zint experienced firsthand how Nextdoor impacts homeless populations. While camping outside of a post office in Berkeley, California with the group First They Came for the Homeless — an organized group of unhoused activists that promotes homeless rights and highlights income inequality in the U.S. — Zint heard rumors about neighbors conspiring against the group on Nextdoor. He used the address of the local post office to create himself a Nextdoor account and read the posts for himself. “I was accused of drug use, theft, and being a criminal,” Zint told East Bay Express at the time. “I was mentioned by name, and most of what was being said was lies.” Zint told OneZero that once Nextdoor discovered he was homeless, his account was removed.

“People post bullshit that sounds like they’re verifiable statements, rather than listening to the voices coming out of the tents,” says Barbara Brust, founder of the Berkeley-based advocacy organization Consider the Homeless. “My biggest fear is that [Nextdoor posters] are influencing people on the fence to be against [the] homeless.”

Anti-homeless sentiment can have real, physical consequences. Speak to enough homeless folks, and you hear stories about acts of vigilantism from housed neighbors. In August, an encampment in the Eagle Rock neighborhood of Los Angeles was purposely set on fire; police have since arrested two men in connection with the arson. According to advocates, violence against the homeless, always a constant, is on the rise.

Nextdoor could help combat these trends by removing the strict requirement of physical addresses in order to access the platform. This would give the homeless residents a way to respond to negative stereotypes or rumors. Another Nextdoor design tweak that might address the platform’s anti-homeless sentiment is making it less private. “When you can see comments people are making in public forums, they become questions that could be dealt with in public,” Kurwa says. “But when it’s hard to get transparency, things can go off the rails very easily without the larger social reckoning.” A simple fix could include only giving post privileges to neighborhood residents, but making the forums viewable to anyone.

Content moderation could also play a role in improving the platform. Currently, Nextdoor has a list of guidelines that posts must follow (for example, “prohibit posts and replies that discriminate against, attack, insult, shame, bully, or belittle others”), but the moderation of these is based on a complaint-based system, meaning that it falls on other members — who, of course, must have physical addresses in the neighborhood to belong to the group — to report bad content. Activists say this system doesn’t work when other neighborhood users feel the same antagonistic way toward homeless folks. A real solution would likely require active human moderators enforcing those guidelines.

“You have to have a living, compassionate person [who] understands, and put in rules that say this will get you banned,” Zint says. “It needs to be controlled.” Administrative platform curation is nothing new — you tend to post more considerately with the looming threat of a ban hanging over your head. It’s unclear whether Nextdoor, now valued at over $2 billion, will make that additional investment.

In the meantime, some Nextdoor forums do police themselves against unfair accusations against homeless populations. “It’s a community effort,” Zint says, “not Nextdoor’s effort.” Without some tweak to the tone of discussions around the homeless population on the Nextdoor platform, activists say, it’ll continue to be a breeding ground for antagonism.

“The end result is that someone is going to get hurt,” Zint says. “That’s how it always ends. It’s always a bad ending for the homeless.”