Ten million users signed up for Meta's newly launched Threads app in its first seven hours, the company's chief Mark Zuckerberg says.
He pitched the app as a "friendly" rival to Twitter, which was bought by Elon Musk in October.
Experts say Threads could attract Twitter users unhappy with recent changes to the platform.
Threads allows users to post up to 500 characters, and has many features similar to Twitter.
Earlier, Mr Zuckerberg said keeping the platform "friendly... will ultimately be the key to its success".
But Mr Musk responded: "It is infinitely preferable to be attacked by strangers on Twitter, than indulge in the false happiness of hide-the-pain Instagram."
When asked on Threads whether the app will be "bigger than Twitter", Mr Zuckerberg said: "It'll take some time, but I think there should be a public conversations app with 1 billion+ people on it.
