San Francisco-based Pinterest has acquired Twitter co-founder Biz Stone's "human powered" search engine start-up Jelly.

"This is the best decision for the future of human powered search and discovery. Jelly plus Pinterest is an exceedingly powerful match. A new adventure begins!" Stone, Co-Founder and CEO, Jelly Industries Inc, said in a statement on Wednesday.

Financial terms of the deals are yet to be disclosed and whether Jelly would remain separate, or integrated was also not revealed.

"We're still working out details, so there are unknowns," Stone said.

Jelly offers a search engine service that answers user's questions in details. To answer the user's questions Jelly routes them to people who might know.

"Human powered search, a subjective search engine, and discovering things you didn't know you need to know. These are all key to Jelly!" Stone said.

But for all the fame of the co-founders and hype when it first launched, Jelly's business never, well, jelled, media reported.

The app has only ranked in the top 1,500 for iOS sporadically since launching in 2014, so it is hard to get reliable download estimates, according to Sergey Bystritskiy, Director of Data Science, SensorTower.

It is currently ranked at No 1,293 for the Social Networking category on iPhone in the US. It is not currently ranking on Google Play ' title=' Google Play '>Google Play in the US, the report said.