Instead, researchers say, interviewers should look for collegiality and a commitment to the business’s strategy and values. “A cultural fit is an individual whose work-related values and style of work support the business strategy,” said Lauren Rivera, who studies hiring at Northwestern’s Kellogg School of Management. “When you get into a lot of the demographic characteristics, you’re not only moving away from that definition but you’re also getting into discrimination.”

They recommend that companies use structured interviews, in which they ask the same questions of every candidate and assign tasks that simulate on-the-job work — and rely on data.

Gild, for instance, uses employers’ own data and publicly available data from places like LinkedIn or GitHub to find people whose skills match those that companies are looking for. It tries to calculate the likelihood that people would be interested in a job and suggests the right time to contact them, based on the trajectory of their company and career.

Mr. Desai said that Gild finds more diverse candidates than employers typically do. In tech, it surfaces more engineers who are women and older and who come from a wider variety of colleges and socioeconomic backgrounds. “If you have white, young male engineers, who are they going to know?” Mr. Desai said. “White, young male engineers.” More than 80 percent of the technical employees at most tech companies are men, and less than 5 percent are black or Latino.

One engineer had applied twice to Rackspace, a cloud computing company, without luck. As an Army veteran who worked in public radio with no high school degree or professional programming experience, he did not fit the pattern that Rackspace looked for. But Gild suggested him based on the software he had been writing on his own, and he was hired.

The tech industry is a focus for some of the hiring start-ups in part because it has more jobs than it can fill, and tech companies are under pressure to make their work forces more diverse. At Twitter, for instance, just 10 percent of technical employees are women, and at Facebook and Yahoo, it’s around 15 percent. Some women and minorities in tech describe an unwelcoming culture, and in response to the criticism, tech companies have begun publishing their diversity data and pledging to make changes.