BOULDER — Just because you’ve built a thriving company doesn’t mean you get to relax.

That’s one of the lessons the 50 employees of SurveyGizmo and its chief executive, Christian Vanek, are learning.

SurveyGizmo’s software helps users, primarily consulting agencies and business marketers, create online surveys and polls.

The company, which incorporated as Widgix LLC in 2006, has seen revenue grow 173 percent over the past two years, from $1.9 million in 2009 to $5.2 million in 2011.

That is enough to place SurveyGizmo No. 3 on the Boulder County Business Report’s Mercury 100 list of fastest-growing private companies in Boulder and Broomfield counties with more than $2 million in annual revenue.

It’s an achievement that “never gets old,” Vanek said, and he should know. This is SurveyGizmo’s third time near the top of the list.

SurveyGizmo mastered the challenges startups face, but now it has a new set of challenges.

“We had figured out what we do, how to do it well, and who our customers are, and we really grew,” Vanek said. “Now there are a whole new set of lessons to learn.”

Many of those lessons touch on the often problematic issues founders face after their companies grow too large for them to be involved in every issue and decision.

“I’m trying to make the switch from a founder’s mentality to a CEO’s mentality. Both personally and as a company, it’s been a real change for us,” Vanek said. “Once you get to 50 employees, it’s not the same game.”

Employees have learned that communicating within a growing company is a challenge. It also is one of the pain points on which SurveyGizmo is looking to capitalize as it enhances its offerings this year.

SurveyGizmo is working to add tools that encourage and aid collaboration to its suite of features. It enables the opinions of users or customers to spread through the company and not be “siloed” in a single department.

“Your entire company can discuss the surveys in a very social way,” Vanek said.

SurveyGizmo also is working to make sure it presents fresh, interesting challenges to employees. The company has started to let small teams of developers dedicate time to projects of their own devising. It’s an idea pioneered by Google, and SurveyGizmo hopes it leads to new features and projects, Vanek said.

The company’s long-term vision is to develop other software suites it can sell alongside SurveyGizmo.