The platform, launched by Instagram-owner Meta, has beaten a record set by Open AI’s ChatGPT app.
Threads went live on Apple and Android app stores in 100 countries, including the UK, last Wednesday.
Meta boss Mark Zuckerberg said he “couldn’t believe” the milestone had been reached so fast.
It hasn’t all been plain sailing for Threads though – it is not available in mainland Europe yet because of uncertainty over whether it complies with EU data privacy legislation.
In his first public comments on the situation, the EU’s industry commissioner Thierry Breton told French radio station, Franceinfo, that “taking a little time to do so seems to me to be probably good policy.”
Despite its problems in the EU Threads has enjoyed rapid growth. Meta, which also owns Facebook, said the app had 10 million users within the first seven hours of launch and more than 30 million by Thursday morning.
Around 24 hours later, that figure had more than doubled.
It still has some way to go to catch its main rival though. At 100 million, Threads’ user base stands at less than a third of the 350 million users that Twitter is believed to have.
Some Twitter users have become disenchanted since billionaire Elon Musk took over. Thousands of jobs have been cut under his ownership and he has announced a number of changes to help generate revenue at Twitter.