The Threads app launched by Instagram as a rival to Twitter has seen more than 100 million users sign up in less than five days, data tracking websites said on Monday, smashing the record of artificial intelligence tool ChatGPT for the fastest-growing consumer app. While ChatGPT took two months to hit the 100-million-user mark and video-sharing app TikTok took nine months, Instagram itself took two and a half years to reach the same 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 due to legal issues the parent company Meta has had with the European Union's data privacy legislation. Twitter is thought to have around 200 million regular users but it has suffered repeated technical failures since Elon Musk bought the platform last year and sacked thousands of staff. Musk, who also serves as the boss of Tesla and SpaceX, has also alienated many users by introducing charges for previously free services and allowing banned right-wing accounts back on the platform.