When I first joined Nextdoor, the hyperlocal social networking site in 2014, I was charmed by neighbors in my East Bay suburb rallying to help one another find lost cats and dogs.

And I continue to appreciate having easy, online access to information about the car break-in up the hill, the best contractor to finish my wood floors, a mother’s campaign to help Nepal earthquake victims or a debate about a controversial new apartment development.

The mission of Nextdoor, a 4-year-old, San Francisco-based startup — which now operates in 70,000 neighborhoods around the country and has recently been valued at $1.1 billion — is to use the power of technology to build stronger and safer communities.

This all sounds very well and good — until you bring real, flawed human beings into the mix. And, then Nextdoor becomes like any social network, with all the good and bad that comes from giving people a venue to let their free expression fly from the remote isolation of their laptops and smartphones.

With Nextdoor, that means bringing people’s sometimes angry, self-righteous, vindictive and socially intolerant comments down to the neighborhood level. Through Nextdoor, where people must use their real names to participate, I’ve learned more than I’d probably like to know about the personal beliefs of people I’d see at my son’s school, shop alongside with at Trader Joe’s or have even had in my home. Sometimes logging onto Nextdoor is enough to make me wonder: Do I really live in the same town as some of these people?

For a long time, I thought I shared the same geography with people who were educated, compassionate and open-minded on public policy and social issues. But maybe I live in a suburb that’s more “Peyton Place.”

While I’ve generally tried to stay out of most Nextdoor discussion threads — I’m worn out from doing my own share of social media venting over the years — it’s been hard to resist chiming in lately when I’ve seen posts from neighbors blaming apartment dwellers or the homeless for the supposed crime wave that’s supposedly overtaken our affluent and statistically safe community. There’s a true culture of fear that pervades some posts on Nextdoor, with maybe a small minority using that fear to justify subtle — or not so subtle — forms of racial profiling.

“You can’t choose your neighbors,” says Andy Smith. He is the co-author of “The Dragonfly Effect,” a book on social media, and is the “lead,” or moderator, for his Lafayette neighborhood’s Nextdoor site. “Most social networks are organized around people’s shared interests, education, professional interests, time of life. It’s more self-selective. With Nextdoor, you bring together people who wouldn’t necessarily hang out together, who are defined by the physical area of the neighborhoods they live in.”

“Neighborly” is Nextdoor’s big buzzword.

In its guidelines, Nextdoor says it encourages civil, polite discussion and discourages posts that are discriminatory. But racial profiling has become an issue on Nextdoor sites around the Bay Area, according to news reports and friends and colleagues from different towns who shared their Nextdoor experiences. Says a Lafayette friend and occasional Nextdoor viewer: “Anyone of color who appears in a neighborhood is suspicious.”

Here’s a recent example from my town: A neighbor alerted people to the fact that he called the police on an African-American man who knocked on his door one afternoon, wanting to talk about real estate.

As the neighbor reported, the police came and determined that the real estate man was legitimate. After letting him go on his way, the officers praised the neighbor and Nextdoor for being proactive in keeping the community safe. So did other people who posted grateful replies to sharing his story.

I definitely didn’t see things the same way and flagged it as inappropriate. For one thing, going door to door may be an old-fashioned method of information gathering, but last I checked, it’s protected activity under the First Amendment.

Meanwhile, I tried to imagine what it must have been like for the man to be stopped by police for simply going about his business. Embarrassing? Frightening? Especially in our era of heightened concerns about racism and police interactions with people of color?

Public shaming is another Nextdoor trend that I’ve heard friends complain about. With the drought, people have used Nextdoor to shame neighbors for overwatering their yards. Going after speeding drivers is another Nextdoor pastime. In my ‘hood, a woman posted a photo of a teen who she said had been driving recklessly; she hoped that people would see his face and tell his parents. Apparently, he was identified, this neighbor proudly reported, and a lot of people thanked her for speaking up.

Again, I didn’t see things the same way. I sent her a private message. Nextdoor encourages people to take their disagreements “offline” and work them out privately. I told this neighbor that I thought she meant well but that she should be careful about publicly accusing someone of criminal behavior, especially a juvenile. She messaged back, but we didn’t come to a friendly resolution. Among other things, she told me my tone was judgmental and cited all the thankful posts she had received.

A few days later, though, I noticed her post was no longer there. Either she reconsidered her position or Nextdoor removed it. Nextdoor spokeswoman Danielle Styskal said public shaming, like racial profiling, violates member guidelines and are addressed by its “dedicated” team of leads. “This is not what being a good neighbor is all about,” she says, adding that such violations are “infrequent” across the network.

Maybe I should take consolation in thinking I did the right thing to chime in. But, no, I feel rather degraded by the whole experience: that these people posted what they did; that so many climbed on their bandwagons; and that I felt the need to tattle on neighbors. I now have a tense relationship with that neighbor in the teen-shaming post and try and avoid passing her house on morning walks.

So much for the neighborly bonds Nextdoor purports to build.

Then again, who’s to blame here? Me? My neighbors? Does Nextdoor simply reflect diverse viewpoints of geographically compact localities, or does its platform somehow amplify divisions?

In any case, I’ll continue to check into Nextdoor for heartwarming stories about lost cats reunited with their owners.

And lately, there’s been this smart, thoughtful discussion about a program to provide overnight shelter this winter to homeless at a local church. Not everyone agrees on the solution, but people are mostly being reasonable and polite in their comments. Now, that’s neighborly.