Terms of the deal for Hotel Tonight, a mobile applications which connects users to hotels for last-minute bookings, were not disclosed.

The deal "accelerates our work to build an end-to-end travel platform that serves everyone," said a statement from Airbnb, one of the largest "sharing economy" startups with a valuation at some $30 billion.

The move comes with Airbnb set to launch a stock listing as soon as this year, in a sign of the maturation of "sharing economy" firms including Uber and Lyft.

HotelTonight's private valuation was estimated at more than $400 million after several funding rounds.

Airbnb's main business is sharing of individually owned properties but it has recently allowed bookings in boutique hotels, bed and breakfasts, and other kinds of accommodations, and the acquisition accelerates that trend.

"Together with HotelTonight, we can offer places to stay for every type of traveler on all kinds of trips and make it easier for small businesses and hoteliers who take pride in providing authentic, unique experiences to tap into Airbnb's truly global network of hosts and guests," the San Francisco-based Airbnb said.

Airbnb has grown from its beginnings in 2008 to become a global giant with some five million listings in 191 countries, but has also faced criticism for alleged unfair competition and for avoiding hospitality taxes.

In one example, Paris city authorities last month sought a fine of 12.5 million euros ($14 million) against Airbnb for 1,000 properties without proper registration.

Under a French law passed in 2018, owners are obliged to register their rentals with tax authorities and display their number on their advertisements, while property owners cannot let them for more than 120 days a year in the biggest cities.