Reddit is one of the most popular sites on the web, with more than 200 million registered users generating over 8 billion page views a month. It allows anyone to create a hub focused on a specific topic, a community where users can share images, links, and thoughts. It was launched over a decade ago, but only released its own mobile app in April of this year. And that app, while solid, is basically a port of its web presence.

Over the past week I spent some time playing with Amino, which has the same underlying purpose as Reddit — user-generated communities based on specific interests — but takes a mobile-only approach that is aimed at a younger audience. The startup, which raised its seed funding in 2014, has around 4 million active users across 92 communities. Today the service is making a big change, one that is likely to supercharge its growth, while possibly exacerbating some of the problems services that rely on user-generated content have struggled with.

Until now, Amino executives decided when to start a new community. Going forward, any user will have the ability to try and start a new interest group. "We wanted to remove ourselves as the bottleneck," said Amino co-founder and CEO Ben Anderson. "The goal is to have a community for every interest in the world."

Before today, the service made each community a dedicated app. This made sense from a distribution standpoint: the audience Amino is pursuing is far more likely to use an app store, not a search engine, when seeking out ways to connect with their passions. You could download a core Amino app that collected all its communities together and made it easy to switch between them. But even though it would be far simpler to use that single core app, Amino says most users who follow multiple topics still use the dedicated apps for each one instead. "People love the feeling of ownership and community that comes with the dedicated apps," says Anderson. "You're entering a world that is built around your interests."

I downloaded several Amino apps that parallel the topics I follow on Reddit, the most active of which was dedicated to Hearthstone, the collectible card game from Blizzard. While the basic idea behind the two services is the same, the mobile nature of Amino leads to some very different behavior. My Reddit feed features a lot of short posts with links to content elsewhere on the web. Most Amino posts are self-contained and are often quite long. Passionate Amino users are even creating their own knowledge base inside these apps, like a Wikipedia-style database covering Korean pop artists, groups, and songs.

And while most discussion on Reddit happens in the comments under posts or in a daily comment thread, Amino apps have dozens of live chat rooms where users go to banter on various topics. On mobile, as always, messaging is a killer feature. You can even search by geography to see nearby Amino users who are interested in the same topic, then check out their posts or request to chat. The downside of the public chat rooms, from my brief experience, was that they could veer dangerously off topic. While moderators on posts in the main room did a good job of keeping the conversation civil, joining a chat room left me with a enormous feed of mobile notifications about anal sex that seemed to have little or nothing to do with Hearthstone.

Anderson, a young man who grew up online, seemed unusually optimistic about dealing with these issues. "Trolls and bad actors exist everywhere there is real-time open, digital communication, including occasionally within our chat rooms. What we see more often than not, is that our users don't give the trolls what they're looking for: an aggressive, defensive response. Because of the strong culture our communities foster, users know how to not give trolls what they're looking for, and eventually those trolls fade away," he argued. "I think that in almost any other similar community, the conversation you highlighted would have quickly devolved into something much uglier, and that it's a testament to the resilience of our community that this didn't and generally doesn't happen. Additionally, our in-house moderation team responds as quickly as possible to any flagged or reported chats."

Opening up community creation will no doubt help to accelerate Amino's already impressive growth. The company offered this new feature to some of its existing user base in a private beta test, and in the first three weeks user launched around 10,000 new communities. The corollary to that, of course, is that Amino will have a much larger, broader pool of content to police. Like all sites based around user-generated content, it will no doubt have its moments of crisis, both ethical and legal, as people push the boundaries of what is acceptable to post.

"Before social networks, forums served a great need as gathering places for vertical passions. Horizontal social platforms like Facebook and Instagram don't super-serve those of us with specific hobbies," says David Pakman, a venture capitalist with Venrock who backed Amino. "Today's digital natives expect mobile-centric sharing communities and yet none exist."

According to the company, less than 10 percent of Amino users are active Reddit users, so the opportunity may be as much about capturing a new generation as taking marketshare from the leader. "These are people who do everything on their phone, and have different expectations about the experience there," says Anderson. Reddit visitors spend an average of 15 minutes on the site. Animo users, the company claims, spend a whopping 40 minutes a day inside the app, typically returning to it 14 times a day. The steady feed of notifications and chats an Amino app delivers is creating a very different kind of community. Reddit is very much still about reading and sharing news. Amino users are more likely to post polls, quizzes, challenges, and essays. "It's about self-expression in a vertical you care about," says Anderson.