The perks of working at a start-up

Gym Running

Recruiters say these kinds of perks help start-ups attract talent. But there's another motive.

We all know about the traditional perks of working at a big company, which can include 401(k) matching funds and stock grants. But start-ups need to be more creative to attract top talent.

One popular perk in the Bay Area: free workouts. Gym memberships can be expensive, so start-ups bring fitness into the office.

At NerdWallet, a personal finance start-up, a boot camp trainer comes to the office and gives its 80 employees a free, hourlong workout. The company's executives say they want to create an atmosphere where employees want to come to work.

"I think boot camp does more for team building than happy hour," said Tim Chen, NerdWallet's CEO. "We end up interacting with people across the company that we don't normally see on a day-to-day basis."

Start-ups also know that mental health is as important as physical health. ZOZI.com is an online service that connects users with local activities and adventures. Its employees take part in rooftop yoga sessions.

Read More Massages, wine-tasting: Hiring perks in Silicon Valley are getting lavish

"Running the largest company doing activity bookings is exciting, but it's a big task," said Daniel Gruneberg, the company's co-founder. "So offering rooftop yoga means our team can take a break during the day, recharge, be healthy and then get back to grow the company together."

Start-ups in the Bay Area also offer perks for getting to and from work. For employees at Evernote-a note-taking app-buying an electric vehicle gets them an extra $250 per month from the company, which is a taxable benefit.

Read More Bubble 2.0? Venture capitalists say no

In California, if you own an electric car, then you can drive in the carpool lane at all hours. That means those Evernote employees get to work a lot faster, and probably arrive in a much-better mood.

Recruiters say these kinds of perks help start-ups attract talent. But there's another motive. When CEOs offer free workouts, food and subsidized transportation, it's one more way to ensure that their workers stay longer at the office.

-By CNBC's Josh Lipton.

Bank Workers CharityBank Workers Charity - Supporting bank workers

Register for Financial Markets News Alerts