Jeremy Allaire has been playing coy with the bitcoin community for months. His Circle Internet Financial has been ranging around, raising money and making plans. But until Friday, nobody knew exactly what it would do.

They know now. Mr. Allaire unveiled the first product at the Bitcoin 2014 conference in Amsterdam, a free financial service aimed at general consumers that will utilize bitcoin’s open-source protocol, but will allow customers to store, transfer and hold currency in local denominations.