Social media isn’t the only place on the internet where extremists are spreading hateful views. Podcasts are also fueling the hate.

Podcasts were once relegated to niche corners of the web, but the format has become much more mainstream in recent years. An estimated 73 million people in the United States tune into a podcast every month, according to Edison Research and Triton Digital.

Extremists, spouting racist, anti-Semitic, homophobic, and anti-immigrant beliefs, have followed the trend and are broadcasting their messages as established social media outlets crack down on similar content.

According to a report released in October by the Anti-Defamation League’s Center on Extremism, podcasting “plays a particularly outsized role in spreading alt-right messages to the world” in 2018. The ADL classifies the alt-right as having a white supremacist ideology combined with several other online subcultures including resentment of women known as “manosphere,” as well as engaging in right-wing conspiracy theories.

Podcasts are one of the most understudied platforms, yet they affect political discourse in big ways, said Alice Marwick, an expert in extremism and an assistant professor at the University of North Carolina at Chapel Hill. There’s a sense of immediacy and authenticity with podcasts, she said.

They’re often unscripted, lengthy, and have the ability to “manufacture consensus,” said Marwick, who is also an adviser at the research institute Data & Society. “Podcasts can add legitimacy to extremist beliefs through repetition and reinforcement.”

Hate speech is harder to pinpoint because audio podcasts are not cataloged by the internet the same way as text, which makes them more difficult to search and to moderate.

Podcasts also spread in myriad ways.

Take LoveStreet, previously known as HateHouse. An episode labeled “HateHouse EP 18: Black people are disabled,” was posted on YouTube nine months ago. Just a few minutes in, one of the speakers says: “Black people look very suspect and they fit the profile for a lot of crimes committed” and “Police know that n****s are violent all the time.” It was removed on Friday after CNN Business flagged the video.

YouTube users often upload podcasts or talk show audio programs to the platform. YouTube’s hate speech policy prohibits content that promotes or condones violence based on characteristics such as race, ethnicity, religion, or sexual orientation, or content that has the purpose of inciting hatred based on those characteristics. But the company has long struggled with policing extremist content.

HateHouse is just one of the podcasts mentioned in the ADL’s report. It’s also available on podcasting platform PlayerFM and PodBean. PlayerFM, which does not post public policies on hate speech, defines itself as a search portal for podcasts, much like a Google search. It does not host podcasts, but disseminates them.

“You are free to access what you’re interested in and not access the ones you’re not. We do carry out moderation of content, for instance, we take down pornographic feeds,” said a PlayerFM spokesperson. For other controversial topics, the spokesperson said it may conduct an evaluation, such as looking at its availability on other podcast directories. Other decision-making processes are unclear.

Another podcast platform called Spreaker has a policy that users may not “publish any content that promotes, either directly or indirectly, hate, racism, discrimination, pornography, violence.” But a search for “Alt Right” turns up episodes from Third Rail podcast, where racism and anti-Semitism abound.

In one episode of Third Rail, labeled as an “ovenside chat,” a guest mentioned the 2014 fatal shooting of black teen Michael Brown at the hands of a white police officer in Ferguson, Missouri. (“Ovenside” is an anti-Semitic term used by several alt-right platforms in reference to the Holocaust.)

“Black lives do matter,” the guest said. “Maybe they shouldn’t be getting killed so much — but they do this to themselves. Try not committing crime, it’s worked for me my entire life.”

Spreaker did not respond to a request for comment.

One of the most popular alt-right podcasts, according to the ADL report, is the The Daily Shoah, created by Mike Peinovich and published on his website, The Right Stuff. The podcast — hosted on another podcasting platform called Libsyn — is peppered with anti-Semitic and white nationalist remarks, including: “We will shut their lying Jew mouths,” “I don’t need foreigners with high IQs in my country. That’s some bullsh*t” and “I want every day back for white normal people. That’s what I’m fighting for.”

Libsyn did not respond to a request for comment.

Episodes are also easily found on YouTube and PodBean under its acronym “TDS.” Peinovich originally hosted The Daily Shoah under a pseudonym, but his identity was revealed in 2017.

YouTube has removed two podcast episodes of The Daily Shoah due to copyright claims. Other extremist podcast episodes flagged by CNN Business remain on YouTube, although some now have offensive content warnings.

“Content of any type that promotes violence or includes hate speech is prohibited on YouTube. We carefully review the videos flagged by our users and remove content that violates our Community Guidelines,” a YouTube spokesperson said in a statement. The company also said it’s training new tech to help flag more hate speech, and its systems are improving.

When reached for comment, PodBean said that while it is not the original host of the podcast, the podcaster submitted The Daily Shoah to Podbean for others to stream. After being alerted to its content by CNN Business, PodBean said, “We have removed it from Podbean directory.”

Another popular podcast and video brand, Red Ice TV calls itself “truly independent alt-media.” The Swedish brand has more than 250,000 subscribers on YouTube. In one radio episode, the speakers mention Somalian pirates and the 2013 film Captain Phillips about the 2009 hijacking of a US container ship by Somali pirates. “From everything I’ve noticed, you guys have a tendency to be bad. Why would you import that?” says one speaker, referring to Somalian people.

Social media platforms, including Twitter and Facebook, have cracked down on threatening speech by kicking off some extremists in a move called de-platforming.

Marwick says this tactic is important, because posting content on more mainstream places helps those with white nationalist, anti-Semitic and homophobic ideas recruit others and direct them to other platforms to consume their message. By de-platforming, it’s harder to spread that content.

InfoWars founder Alex Jones has been kicked off sites such as YouTube, Facebook, Twitter and Spotify for violating their policies like rules around hate speech, although Spreaker makes available some InfoWars podcasts.

Extremists and their followers are still using some social platforms to relay information to each other and create fans.

Peinovich, for example, is an active Twitter user. His feed consists of white nationalist commentary and tweets that include statements such as “the left wants all white people dead and openly says so with regularity.”

“The goal is to post content on the more mainstream platforms and reel them in,” said Marwick.

By piquing curiosity on Twitter, users may seek out more information about a person and stumble upon their podcasts, Marwick added.

Mark Pitcavage, a senior research fellow at the Anti-Defamation League’s Center on Extremism who worked on the report, told CNN Business that where technology advances, the extremists follow.

“Podcasting is one of the main ways the alt-right is getting its message out to its own members,” said Pitcavage, noting that platforms may not be sufficiently aware of the issue yet.

A Reddit post earlier this year asks, “What are the best Alt-Right podcasts?”

“There’s just so many of them and I don’t really know where to start,” the user said when asking for recommendations.