SAN FRANCISCO >> Airbnb is acquiring last-minute booking service HotelTonight in order to boost its offerings.

The two San Francisco-based companies announced the deal today. Terms weren’t revealed.

HotelTonight co-founder and CEO Sam Shank will lead Airbnb’s boutique-hotel category.

HotelTonight will operate separately, offering discounted rooms for last-minute trips. It has partnerships with thousands of hotels in North and South America, Europe and Australia.

Gradually, some of those rooms — particularly ones in boutique hotels — will also be offered by Airbnb. Airbnb may also direct users to HotelTonight to help them find last-minute properties.

Airbnb lists more than 6 million places to stay worldwide. Last year, it doubled the number of hotels and bed and breakfasts on its site in order to meet users’ demands.