Cold brew is always on tap at HubSpot Inc.’s headquarters in Cambridge, where the kitchen has a designated beer fridge stocked with at least 50 different brands. “We have Stella, Beck’s, Guinness, Bud Light,’’ said Kara Sassone, the company’s media relations specialist, as she rattles off the more popular labels.

A cold one helps to encourage employees to hang out at the office and build better working relationships, the company says. Free or not, beer -- as with all good things -- is best in moderation, especially at the office.

Even so, it’s a popular perk. “I’m sure if we were to get rid of the beer fridge here at HubSpot, the whole company would be up in arms,’’ blogged one employee.