Imzy tries to combat some of those issues through the site’s architecture. When someone signs up, they are directed to pick a few specific communities they want to join. That’s different from Reddit’s “front page,” which displays a smattering of different popular subforums to new users.

The idea, Mr. McComas said, is that the core, devoted members of a group are often not the ones who make a community toxic, but rather the passers-by who may stumble upon a new community and leave disparaging remarks.

Imzy users are also allowed to select only one username in each community they join, to keep trolls from creating multiple identities with which they can harass others. Individual moderators self-govern their communities, based on rules of their own making, giving each community the flexibility to set its own terms about what is and is not permissible. Other conventions, like chatting in threads and posting images, are much the same as predecessor sites.

“We’re building this way because we want people to find and join communities that they have a real connection to, and these are really our first measures to address the problems in the way of getting there,” Mr. McComas said.

He is also expanding Imzy slowly — people need an invitation to participate, and users can invite only a handful of others once they have joined. Imzy has partnered with other culture groups and celebrities, including the “Girls” creator Lena Dunham, to bring their own internet fan bases to the platform.

“Everyone becomes their Mr. Hyde selves on the internet,” said Shawn Kittelsen, creative director of Feral Audio, a podcast network that is working closely with Imzy to start an online community for its listeners. “The bottom line is, do you have a system to help manage the bad eggs so that they don’t ruin the experience for everyone else?”

Imzy has a hard road ahead before reaching the mainstream. The site hosts 15,000 users, and 20,000 more are on the waiting list, a paltry number compared with the hundreds of millions of users who visit Reddit and other competing sites.