*

TikTok stops working in US before federal ban Sunday

*

Trump says 'SAVE TIKTOK!' in Truth Social post

*

Supreme Court upholds ban, Biden does not intervene

*

Users explore alternatives, rivals see shares rise

By David Shepardson

WASHINGTON, Jan 19 (Reuters) -

TikTok stopped working for its 170 million American users

late on Saturday before a law shutting it down on national

security grounds took effect on Sunday, but a day before his

inauguration, President-elect Donald Trump said "SAVE TIKTOK!"

in a Truth Social post.

Trump had earlier said he would "most likely" give

TikTok a

90-day reprieve

from the ban after he takes office on Monday, a promise

TikTok cited in a notice posted to users on the app.

"A law banning TikTok has been enacted in the U.S.

Unfortunately, that means you can't use TikTok for now. We are

fortunate that President Trump has indicated that he will work

with us on a solution to reinstate TikTok once he takes office.

Please stay tuned," a message notified users of TikTok, which

disappeared from Apple ( AAPL ) and Google app stores late on Saturday.

Even if temporary, the unprecedented shutdown of TikTok,

owned by China's ByteDance, is set to have a wide-ranging impact

on U.S.-China relations, U.S. domestic politics, the social

media marketplace and millions of Americans who depend on the

app economically and culturally.

The United States has never banned a major social media

platform. The law passed overwhelmingly by Congress gives the

incoming Trump administration sweeping authority to ban or seek

the sale of other Chinese-owned apps.

Other apps owned by ByteDance, including video editing app

CapCut and lifestyle social app Lemon8, were also offline and

unavailable in U.S. app stores as of late Saturday.

"The 90-day extension is something that will be most likely

done, because it's appropriate," Trump told NBC. "If I decide to

do that, I'll probably announce it on Monday."

It was not clear if any U.S. users could still access the

app, but it was no longer working for many users, and people

seeking to access it through a web application were met with the

same message that TikTok was no longer working.

TikTok, which has captivated nearly half of all Americans,

powered small businesses and shaped online culture, warned on

Friday it would go dark in the U.S. on Sunday unless President

Joe Biden's administration provided assurances to companies such

as Apple ( AAPL ) and Google that they will not face

enforcement actions when a ban takes effect.

MOVE TO ALTERNATIVES

Under the law passed last year and upheld on Friday by a

unanimous Supreme Court, the platform had until Sunday to cut

ties with its China-based parent or shut down its U.S. operation

to resolve concerns it poses a threat to national security.

Biden's White House reiterated on Saturday that it was up to

the incoming administration to take action.

"We see no reason for TikTok or other companies to take

actions in the next few days before the Trump administration

takes office on Monday," press secretary Karine Jean-Pierre said

in a statement.

TikTok did not respond to a request for comment on the White

House statement.

The Chinese embassy in Washington on Friday accused the U.S.

of using unfair state power to suppress TikTok. "China will take

all necessary measures to resolutely safeguard its legitimate

rights and interests," a spokesperson said.

Uncertainty over the app's future had sent users - mostly

younger people - scrambling to alternatives including

China-based RedNote. Rivals Meta and Snap have

seen their share prices rise this month ahead of the ban, as

investors bet on an influx of users and advertising dollars.

"This is my new home now," wrote a user in a RedNote post,

tagged with the words "tiktokrefugee" and "sad".

Minutes after TikTok's U.S. shutdown, other users took to X,

formerly called Twitter.

"I didn't really think that they would cut off TikTok. Now

I'm sad and I miss the friends I made there. Hoping it all comes

back in just a few days," wrote @RavenclawJedi.

'HAIR ON FIRE' MOMENT

NordVPN, a popular virtual private network, or VPN, allowing

users to access the internet from servers around the world, said

it was "experiencing temporary technical difficulties."

Web searches for "VPN" spiked in the minutes after U.S.

users lost access to TikTok, according to Google Trends.

Users on Instagram fretted about whether they would still

receive merchandise they had bought on TikTok Shop, the video

platform's e-commerce arm.

Marketing firms reliant on TikTok have rushed to prepare

contingency plans in what one executive described as a "hair on

fire" moment after months of conventional wisdom saying that a

solution would materialize to keep the app running.

There have been signs TikTok could make a comeback under

Trump, who has said he wants to pursue a "political resolution"

of the issue and last month urged the Supreme Court to pause

implementation of the ban.

TikTok CEO Shou Zi Chew plans to attend the U.S.

presidential inauguration and attend a rally with Trump on

Sunday, a source told Reuters.

Suitors including former Los Angeles Dodgers owner Frank

McCourt have expressed interest in the fast-growing business

that analysts estimate could be worth as much as $50 billion.

Media reports say Beijing has also held talks about selling

TikTok's U.S. operations to billionaire and Trump ally Elon

Musk, though the company has denied that.

U.S. search engine startup Perplexity AI submitted a bid on

Saturday to ByteDance for Perplexity to merge with TikTok U.S.,

a source familiar with the company's plans told Reuters.

Perplexity would merge with TikTok U.S. and create a new entity

by combining the merged company with other partners, the person

added.

Privately held ByteDance is about 60% owned by institutional

investors such as BlackRock and General Atlantic, while its

founders and employees own 20% each. It has more than 7,000

employees in the U.S.

(Reporting by Jaspreet Singh, Aditya Soni in Bengaluru and

Mrinmay Dey, David Shepardson in Washington, Doyinsola Oladipo

in New York, Kenrick Cai and Noel Randewich in San Francisco,

and David Ljunggren in Ottawa;

Editing by Nick Zieminski, Rod Nickel, Heather Timmons, Daniel

Wallis, Deepa Babington, William Mallard, Kim Coghill and Ros

Russell)