TikTok is resuming services to its 170 million users in US after President-elect Donald Trump said he would give the app a reprieve when he takes office on Monday.
On Sunday the Chinese-owned app stopped working for American users, following concerns that their data could be accessed by Chinese officials.
In a statement, TikTok later said it was in the process of "restoring service" just hours after going dark in America.
It thanked the president-elect for "providing the necessary clarity and assurance" and said they would work with Trump "on a long-term solution that keeps TikTok in the United States".
Posting on Truth Social, a social media platform he owns, Trump said on Sunday, external : "I'm asking companies not to let TikTok stay dark! I will issue an executive order on Monday to extend the period of time before the law's prohibitions take effect, so that we can make a deal to protect our national security."
TikTok's parent company, Bytedance, previously ignored a law requiring it to sell its US operations to avoid a ban. The law was upheld by Supreme Court on Friday and went into effect on Sunday.