Parler grew slowly until early 2020, when Twitter began labeling Mr. Trump’s tweets as inaccurate and some of his supporters joined Parler in protest. After November’s election, Parler grew even more quickly as Facebook and Twitter clamped down on false claims that the vote had been rigged. So many users signed up that, at times, they overloaded the company’s systems and forced it to pause new registrations.

In total, people downloaded Parler’s app more than 10 million times last year, with 80 percent in the United States, according to Sensor Tower, the app data firm.

Last Wednesday, Mr. Trump encouraged his supporters to march to the Capitol to pressure lawmakers to overturn his election loss, leading to a rampage that left five people dead. The rally was planned on Facebook, Twitter and elsewhere. On Parler, people posted advice on which streets to take to avoid the police; some posted about carrying guns inside the Capitol.

In an interview with The New York Times hours after the mob stormed the Capitol, Mr. Matze said, “I don’t feel responsible for any of this and neither should the platform, considering we’re a neutral town square that just adheres to the law.”

But on Friday, Apple and Google told Parler that it needed to more consistently remove posts that encouraged violence. By Saturday, Apple and Google had removed Parler from their app stores, limiting its ability to reach new users on virtually all of the world’s smartphones.

“There is no place on our platform for threats of violence and illegal activity,” Apple said in a statement. Google said, “We do require that apps implement robust moderation for egregious content.”

Late Saturday, Amazon told Parler that it would need to find a new place to host its site. Amazon said it had sent Parler 98 examples of posts on its site that encouraged violence, but many remained online.