Can Reddit keep its hot streak going?

Savvy web-searchers treat the social content-sharing service’s forums as a more reliable alternative to the open internet, an oasis of human-written chatter in a desert of webspam, sponcon and bots.

“It adds a layer of real world experience and real-time intel to things," said Cristin Culver, a communications consultant in Austin, Texas, who recently used Reddit to plan a trip to Las Vegas.

Lately, artificial intelligence labs have regarded Reddit in much the same way, striking licensing deals to bring Reddit’s content to their products. Those deals are a high-margin complement to its ad business, which grew 84% year-over-year to $465 million in the second quarter.

Add it all up and Reddit is having a moment. Daily visitors are up 21% year-over-year, the company posted its most profitable quarter ever in July, and bullish investors have sent its stock up 158% over the past year.

But AI isn’t just a source of new revenue for the company. It’s also a threat.

Culver planned her Vegas itinerary not by searching Reddit directly, but by asking ChatGPT to search it for her. That type of behavior is worrisome for a company that’s focused on growing the number of users who go directly to the app and post there regularly.

Reddit began testing a new search bar in its app last year that makes it easier for users to find relevant conversation threads within the app, versus through Google or ChatGPT. The company has since expanded the rollout of the chatbot-like search tool called “Reddit Answers" a few times, most recently last week.

At the same time, Reddit has to defend its forums from being swamped with AI-generated text, a development that could diminish its utility to large language models and weaken the sense of community that keeps users coming back.

The company is banking on being able to maintain the quality and authenticity of the content on its platform, even against a deluge of AI, Chief Operating Officer Jen Wong said in an interview.

“We’ve been fighting bots for 20 years," she said.

In the future, Wong argued, Reddit’s data will only become more valuable to AI companies. “Who is going to review a new car? Humans who sat in it. Who’s going to tell you what the food tastes like? Someone had to eat it," she said.

Both OpenAI and Google have multimillion-dollar licensing deals with Reddit. Rich Greenfield, an analyst with LightShed Partners, said he expects the value of those deals to rise over time.

In June, Reddit sued AI chatbot maker Anthropic for using its data for commercial purposes without a licensing agreement. The complaint references a 2021 research paper from Anthropic that details the usefulness of Reddit’s data in its training. Anthropic said at the time that it disagreed with Reddit’s claims and would defend itself vigorously.

In a recent study of 150,000 user-generated content citations across the web, Reddit was overwhelmingly the most used source at 40%. YouTube and Facebook accounted for 23% and 20% of citations, respectively, according to Semrush, the digital marketing platform that ran the study.

“They are perceived as having real human communication," said Imri Marcus, chief executive of Brandlight, a marketing AI insight tool. “A lot of their future success—on whether AI LLMs will choose to quote them—will be around whether they can protect the quality of that town square."

For some users, AI has already degraded the experience on Reddit.

For 15 years, Jeffrey M. Hart used Reddit like his own “personalized newspaper," scouring the website for random tidbits and expert takes.

In the past year, he has noticed more activity by bots, some of which post what seems to be engagement bait—for instance, a wrong answer that prompts other users to pile on with corrections.

“It totally takes away the human connection," said Hart, who lives in Atlanta.

From January to June of this year, Reddit’s administrators and volunteer moderators removed more than 158 million pieces of content, according to the company’s latest transparency report. That’s slightly down from 162 million in the year-earlier period.

Wong said the company continues to look for ways to ensure its platform remains by humans, for humans: “Our goal is to have people find their home on Reddit."

Write to Meghan Bobrowsky at meghan.bobrowsky@wsj.com and Ann-Marie Alcántara at ann-marie.alcantara@wsj.com