SAN FRANCISCO — In February, about a dozen employees at a small technology company called NPM embarked on an effort that is often frowned upon at start-ups: trying to unionize.

For more than three months, the workers had battled the company’s new management over their hours, a changing workplace culture and diversity issues, said seven current and former NPM employees. So to give themselves more say, they moved to organize. The employees contacted labor groups, including the International Federation of Professional and Technical Engineers and the Tech Workers Coalition, to hold unionization discussions.

“We wanted the leverage to negotiate for things that were important to us as workers, rather than having them told to us,” said Graham Carlson, who was a content marketing manager at NPM, which provides tools to web developers. “We felt the best way to address it was to address it collectively.”

Three weeks after the workers began organizing, NPM laid off Mr. Carlson and four other employees, all but one of whom had been involved in the unionizing. After some of those employees filed a formal charge with the National Labor Relations Board, the federal agency that oversees such complaints, NPM settled with the workers last month. No union has been formed.