Assuming contract work does not violate their current work agreements, Mr. Bischke said, prospective hires at Entelo are given part-time projects to work on at night or over the weekend. They are paid, he said, a “solid consulting rate” for this work, and the trial period can last two to four weeks. About half of the 30 people who have been asked to work on a trial basis have moved into full-time jobs, he said. In some cases it didn’t work out because the candidates had a change of heart. In others, he said, “Let’s just say that had we hired them, we probably would have had to fire them.”

At Joor, prospective employees are hired on a temporary contract for three months, over which time they are given 30-day milestones. If they reach those milestones, they stay on. “If we realize it’s not a good fit, we’ll end the relationship before that,” Ms. Bijoor said, noting that candidates are generally eager to test the waters before committing to a job and that they are treated legally as employees even during the trial period.

“We find people who are in jobs where they are unhappy,” she said. “They are willing to take the risk because they believe in what we are doing or see themselves working for a start-up. It’s not conveyed as a one-way benefit for Joor. We want to make sure Joor is the right fit for them, too.”

It is far easier for both the employee and the boss to back out of a temporary arrangement than to terminate employment. “We’ve found it actually helps with recruiting,” said David Rusenko, chief executive and co-founder of Weebly, a company based in San Francisco that creates and hosts websites. “I’ve had people say they can’t imagine accepting a job just a couple of hours after meeting someone.”

For Weebly, the idea started in 2008 when Mr. Rusenko and his co-founders were hiring their first outside employee, a graphic designer. They asked each candidate to do a project so the work could be assessed. They used the same approach for their next hire, and so on.

“Now we’re at about 150 employees, and just about every single one of them has gone through a trial week,” Mr. Rusenko said. “It’s turned into a cornerstone of our culture.”

During trial weeks, Weebly brings candidates into the office to work on a well-defined project. “We tell people to take a vacation, and we pay them,” he said. That way, if it does not work out, “you have one less week of vacation, but the next time you take a vacation it can be a nicer one.”