Its products were among the first fitness trackers on the market and it was once valued at more than $3bn.
The firm had been silent on social media for several months and customers with broken devices had contacted the BBC to say they could not get a response.
Jawbone trackers are still available to buy from websites including Amazon.
The anonymous messaging app had raised more than $73m in funding and was at one time valued at $400m.
The platform was hugely popular with college students but it was also plagued with incidents of online harassment and bullying. The firm attempted to enforce permanent log-ins but it proved unpopular.
Yik Yak announced that it would close at the start of the academic year.
Its website has now disappeared but in a blog post published at the time of the announcement, founders Brooks Buffington and Tyler Droll thanked Yik Yak users for being “the most passionate on the planet”.