Andrea Vaccari recently faced a grueling decision: whether to accept an offer from Facebook Inc. for his 18-month-old start-up, or go for broke.

He and his co-founders had poured their money and energy into Glancee, which made a mobile application designed to help people find others with similar interests, and the app was finally taking off.

But the company was almost out of cash. The 29-year-old Mr. Vaccari was living out of a closet in a friend's apartment.

In May, Glancee's owners decided to accept an "acqui-hire" offer from Facebook, even though they knew the offer's primary purpose was to recruit them as software engineers. Now they work for the social-networking giant.

Established technology companies increasingly are buying—and then shutting down—early stage start-ups, mostly to acquire their software-engineering talent.