Menlo Park, California - Threads, Meta's new alternative to Twitter, has signed up more than 100 million users in less than five days, data tracking websites said on Monday, smashing ChatGPT's record for fastest-growing consumer app.

While ChatGPT took two months to hit the 100 million user mark and TikTok took nine, Instagram itself took two and a half years to reach that mark after its 2010 launch.

Threads went live on Apple and Android app stores in 100 countries late on Wednesday, though it is not available in Europe because parent company Meta is unsure how to navigate the European Union's data privacy legislation.

Twitter is thought to have around 200 million regular users but it has suffered repeated technical failures and since Elon Musk bought the platform last year and fired thousands of staff.

Musk, who also serves as the boss of Tesla and SpaceX, has also alienated many users through his erratic decision-making and by introducing charges for previously free services, as well as allowing banned far-right accounts back on the platform.

He has threatened to sue Meta for stealing trade secrets and intellectual property, and spent the weekend calling Meta chief Mark Zuckerberg a "cuck" and demanding a "a literal d*** measuring contest."

Threads is linked to Instagram, which has more than one billion regular users.