Meta has unveiled an app called Threads to rival Twitter, targeting users looking for an alternative to the social media platform owned — and frequently changed — by Elon Musk.

Threads is billed as a text-based version of Meta's photo-sharing app Instagram that the company says provides "a new, separate space for real-time updates and public conversations."

It went live late Wednesday in Apple and Google Android app stores, with CEO Mark Zuckerberg saying 10 million people had signed up in the first seven hours. There were some early glitches, including Zuckerberg's posts — or Threads as they're dubbed — not loading in several places including the United Kingdom, India and Lebanon. But his replies to other users did appear.

Threads launched in more than 100 countries — including the U.S., Britain, Australia, Canada and Japan — and has already drawn celebrity users like chef Gordon Ramsay, pop star Shakira and actor Jack Black as well as accounts from Airbnb, Guinness World Records, Netflix, Vogue magazine and other media outlets.

The Twitter-like microblogging experience suggests that Meta Platforms has been gearing up to directly challenge the platform after Musk's tumultuous ownership has resulted in a series of unpopular changes that have turned off users and advertisers.

Zuckerberg said in some early replies on Threads that he's focused on making the app "a friendly place," which will "ultimately be the key to its success."

"That's one reason why Twitter never succeeded as much as I think it should have, and we want to do it differently," he wrote.

On Threads, there are buttons to like, repost, reply to or quote a thread, and users see the number of likes and replies that a post has received.

Posts are limited to 500 characters, which is more than Twitter's 280-character threshold, and can include links, photos and videos up to five minutes long.

Despite that, Meta said its "vision is that Threads will be a new app more focused on text and dialogue, modeled after what Instagram has done for photo and video."

Instagram users will be able to log in with their existing usernames and follow the same accounts on the new app. New users will have to set up an Instagram account.

Meta emphasized measures to keep users safe, including enforcing Instagram's community guidelines and providing tools to control who can mention or reply to users.

Meta's new offering, however, has raised data privacy concerns.

Threads could collect a wide range of personal information, including health, financial, contacts, browsing and search history, location data, purchases and "sensitive info," according to its data privacy disclosure on the App Store.

Twitter co-founder Jack Dorsey pointed it out in a snarky tweet saying, "All your Threads are belong to us" that included a screenshot of the disclosure. Musk replied "yeah."

One place Threads won't be rolled out is in the European Union, which has strict data privacy rules.

Meta has informed Ireland's Data Privacy Commission that it has no plans yet to launch Threads in the 27-nation bloc, commission spokesman Graham Doyle said. The Irish watchdog is Meta's main privacy regulator for the EU because the company's regional headquarters is based in Dublin.

The company is working on rolling the app out to more countries but pointed to regulatory uncertainty for its decision to hold off on a European launch.

Analysts said its success is far from guaranteed, citing Meta's track record of starting standalone apps that were later shut down. Also in question is whether it's the right move for Meta, which announced tens of thousands of layoffs over the past year amid a tech industry slowdown.

Zuckerberg also has been focusing on the metaverse, investing tens of billions of dollars in the virtual reality concept.

Meta risks "spreading itself too thin," said Mike Proulx, a research director at Forrester, a global market research company. "Meta is banking on a moment in time amidst peak Twitter frustration. However, this window of opportunity is already flooded with Twitter alternatives including Bluesky, Mastodon, Spill, Post.News and Hive, which are all competing for Twitter's market share."

Even so, Threads could be a fresh headache for Musk, who acquired Twitter last year for $44 billion.

He's made a series of changes that have triggered backlash, the latest being daily limits on the number of tweets people can view to try to stop unauthorized scraping of potentially valuable data. He also is now requiring paid verification for users to access the online dashboard TweetDeck.

Musk's rivalry with Zuckerberg could end up spilling over into real life. In an online exchange the two tech billionaires seemingly agreed to a cage match face-off, though it's unclear if they will actually make it to the ring.

Amid the Threads launch, Musk responded to a tweet showing a screenshot of him saying he deleted Instagram in 2018 because it was "weak sauce."

"It is infinitely preferable to be attacked by strangers on Twitter, than indulge in the false happiness of hide-the-pain Instagram," he said.