Peter Thiel just joined the board of a startup that's secretly raised $50 million over the last three years

WiFi startup Zenreach has officially emerged from stealth mode, announcing that it's raised $50 million and added Peter Thiel to its board.

Zenreach uses WiFi to help merchants find out how many times a customer returns to a store. When customers login to a store's free, customized WiFi with their email addresses, merchants can track how many times customers return.

The company has remained quiet for the last three years, but despite the low profile, Zenreach has grown to a staff of 150 and raised $50 million through three funding rounds - including a $30 million Series B round led by Founders Fund founder and Facebook board member Peter Thiel, according to a blog post by Zenreach founder Jack Abraham.

"Online merchants rely on sophisticated analytics and marketing campaigns to attract customers," Thiel said in a statement. "Zenreach levels the playing field for brick and mortar businesses by arming them with equally powerful tools."

Zenreach's other investors include 8 VC, Bain Capital Ventures, First Round Capital, Felicis Ventures, SoftTech VC, and SV Angel. The company plans to use its latest investment to grow to 300 employees and open a new international office in Dublin, according Forbes reporter Alex Konrad.