But billionaire Bill Gates isn't a fan of the platform, calling some of its content "crazy stuff."
If somebody goes to Parler, they are saying, "I like crazy stuff," Gates said Tuesday at The New York Times DealBook Summit. "If you want Holocaust denial, hey, Parler is going to be great for you," Gates said.
(In October, Facebook announced a ban on content denying or distorting the Holocaust, classifying it as hate speech. Parler, however, does not police any content on its platform, so popular but controversial topics that appear on the site include voter fraud, Holocaust denial and anti-Semitic remarks, according to the Anti-Defamation League.)
Parler, which was founded by Mercer, John Matze and Jared Thomson in 2018, was the most downloaded app for both Android and iPhone users during the week of Nov. 9 to Nov. 15, according to SensorTower, a marketing intelligence company that tracks app downloads. For the week starting on Nov. 16, Parler has so far fallen to No. 2 among Android users and No. 11 among iPhone users.
The app has attracted the likes Fox Business host Maria Bartiromo, Republican Texas Sen. Ted Cruz and celebrities Kristie Alley and Scott Baio. On Nov. 12, Wired reported that Parler grew from 4.5 million users to more than 8 million, compared to Twitter's 330 million users and Facebook's more than 2 billion.
Many high-profile conservatives have been urging their followers to join Parler after Twitter and Facebook have been adding alerts to posts that spread misinformation, including to posts shared by President Donald Trump about election and voter fraud.
Gates, who has been targeted by online anti-vaxxer conspiracy theorists (who believe Gates is trying to microchip humans through coronavirus vaccines, an accusation to which there is no truth), said there needs to be regulation to manage misinformation on social media platforms.
"Facebook services are the primary way people access news and they get drawn in to more and more extreme stories, including some of these anti-vaccines or conspiracy things," Gates said at DealBook.
"So that person who hasn't started out saying, 'I want crazy stuff,' they get drawn down and see things that are very titillating and that is where it is almost a human weakness," Gates said.
Asking social media platforms to "be the arbiter of all these things is pretty tough," Gates said. But over the last few months, particularly around medical information, Gates said social media platforms like Facebook and Twitter have been doing a better job at screening posts and adding labels to misinformation.
"I think we are sort of finding our way, which will be either leave it alone all the time or strict liability, which you know if you got strict liability, it's not clear that they can even stay in business," Gates said at DealBook. (Strict liability is a legal construct that holds a party responsible for injuries caused by its actions or products, without the need for negligence or fault.)
A spokesperson for Twitter tells CNBC Make It that its users are the ones who requested "more context around high profile content that has the potential to cause offline harm, particularly around elections."
Representatives for Parler and Facebook did not immediately respond to Make It's request for comment.
This story has been updated to include a statement from Twitter.