– Groupon Inc., the biggest daily deal website, is adding an online restaurant-booking service offering discounted meals as the company seeks to bolster revenue amid waning demand for its Web-based coupons.

The service, called Groupon Reserve, will let customers use Savored.com's reservations engine to find tables, Chicago-based Groupon said Monday in a statement. It's already live in 10 cities: Atlanta, Boston, Chicago, Denver, Los Angeles, Miami, New York City, Philadelphia, San Francisco and Washington, and will expand in the United States and overseas later this year.

Groupon, which started out promoting discounts via e-mail alerts, is challenging existing reservation services by companies such as Open­Table Inc. as consumers are buying fewer daily deals. Unlike other Groupon discounts, the restaurant platform will give users a discount off their bill without requiring prepayment or vouchers.

"As Groupon has evolved, we've seen growing demand from our customers for upscale offers and exclusive experiences," co-Chief Executive Eric Lefkofsky said in the statement. "Reserve gives the most prestigious brands a new way to reach our large and desirable audience."

Groupon Reserve will also add premium deals for beauty, travel and entertainment brands as well as bookings for spas, salons and hotels.

The company makes money by offering consumers discounts — known as Groupons — from businesses such as restaurants and nail salons. It then shares the revenue with the businesses.

Shares of Groupon rose 1.4 percent to $8.67 at the close in New York. The stock has advanced 78 percent this year, compared with a 13 percent gain for the Standard & Poor's 500 Index. OpenTable closed unchanged at $63.95, leaving the shares up 31 percent this year.