John Matze, the chief executive of the embattled social media platform Parler, said on Wednesday that he was fired last week.
Mr. Matze, 27, who co-founded the site in 2018, said in an interview that he was not given an explanation for the decision. He said he believed he was fired because of a difference in opinion with the prominent Republican political donor Rebekah Mercer, who supports Parler financially.
Ms. Mercer, he said, did not seem to want to impose any restrictions on what users could say on Parler, which has billed itself as a “free speech” social network. While that open philosophy made the site popular with conservatives, it also led to trouble.
Last month, Parler was removed from Apple’s and Google’s app stores and booted from Amazon’s web-hosting platform for not being strict enough in policing and removing posts that tried to incite violence or crime.
“I’ve always been about free speech and everyone being welcome. I’ve never been about conservative political activism,” Mr. Matze said. But he said he had told Ms. Mercer that Parler needed to consider restricting domestic terrorists, white supremacists and members of QAnon, the baseless pro-Trump conspiracy theory, from posting on the platform.
“I got dead silence as a response, and I took that dead silence as disagreement,” he said.
Millions of people began flocking to Parler, a platform similar to Twitter, after the November presidential election, when mainstream sites like Facebook and Twitter became more aggressive about curtailing hate speech and misinformation. Last month, after a mob of former President Donald J. Trump’s supporters stormed the U.S. Capitol, partly at Mr. Trump’s urging, Twitter and Facebook cut him off from their sites entirely.
But Parler was not able to capitalize on the interest from right-wing users for long. After Apple, Google and Amazon declined to work with the company, citing Parler’s lack of policing of its platform, the site went dark on Jan. 11.
Mr. Matze had been trying to find a way to get Parler back online. The company sued Amazon last month for antitrust violations. Parler also sought help from a Russian internet security company, DDoS-Guard, to get a basic webpage back up, though users have been unable to post.
Neither a Parler spokeswoman nor Ms. Mercer immediately responded to requests for comment.