Last year we profiled Web engineering company 10up (which developed this website). Aside from its near-fanatical devotion to all things WordPress, one of the hallmarks of 10up is that it’s a distributed company—its 60-plus full-time developers and project managers live and work all over the country. That model is catching on, with “virtual” companies becoming more and more common in the tech sector. Some, like Mozilla, Basecamp, and Upworthy, are fast-growing software or media companies. Others are developers, marketers, digital designers, or online learning platforms. “Web based” best describes all of the companies that made a list compiled by job search site FlexJobs (which has the distinction of appearing on its own list), but each blend offline and online collaboration in different ways and to varying degrees. A recent New York Magazine profile of Upworthy illustrates that although the company invites its workforce to “work from home, from a coffee shop, from a coworking space—anywhere with good enough Internet to do a Google Hangout,” the leadership team convenes regular in-person strategy meetings. Footwear is optional.