In 2003, Craig Nevill-Manning, a computer scientist at Google, wanted to set up an engineering outpost in New York. Google’s top leaders were skeptical, but they told him that he could go ahead if he could find 15 “Google-worthy” software developers in the city.

“The attitude was that pretty much all the good software engineers were in Silicon Valley,” Mr. Nevill-Manning recalled. “It seems crazy in retrospect.”

Mr. Nevill-Manning found his developers and opened the engineering office in New York. Today, Google employs 7,000 people in the city, and more than half are engineers and technical staff.

The Google story mirrors the rise and evolution of New York as a genuine tech hub — home to a deep pool of technical talent as well as sales, marketing and business expertise. And Amazon’s decision to put a headquarters in the city, eventually employing more than 25,000 workers, only reinforces that trend.