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Tuesday is Equal Pay Day — the day women's earnings "catch up" to men's earnings from the previous year. It's also a great day to raise awareness about America's persistent gender pay gap. Although more than 50 years ago President Kennedy signed the Equal Pay Act, making it illegal for employers to pay unequal wages to men and women who perform the same work, little progress has been made: Women are still typically paid just 80 cents on every dollar paid to men. And newly proposed federal legislation aimed at helping to close the loopholes in the Equal Pay Act— known as the Paycheck Fairness Act — has been stalled for years in Congress. With many women now the breadwinners in 40 percent of households, compared with just 11 percent in 1960, the gender gap is no longer a women's issue but a family issue. InHerSight is helping to change that.

The data difference

To hear InHerSight founder Ursula Mead explain it, talk is cheap. But data can make a difference. In 2013, while still vice president for premium memberships at The Motley Fool, Mead began working on the idea of a datacentric platform that could address — and potentially change — the challenges women still encounter today when it comes to equal pay, looking to find a job or move up in their companies. What emerged is InHerSight (No. 24 on CNBC's Upstart 25 list), an online platform that lets women anonymously rate their current or former employers on 15 metrics, such as management opportunities, maternity leave, salaries and ability to telecommute. Based on the feedback, companies are given a score from one to five stars. Today the company claims that more than 200,000 women have used InHerSight to rate 31,000 companies in the United States, including Coca-Cola, Amazon and Google, or get matched to companies that have what they're looking for. At a time when gender inequality is being addressed on a global scale — Iceland recently became the first country to introduce legislation requiring employers to prove they are paying men and women equally — InHerSight lets women speak out about specific companies and the changes still needed to level the field.

"Back when I first started thinking about the business, there were all these conversations happening around women taking charge of their careers, and what success did or didn't look like," says Mead. In fact, just a year earlier she had read Anne-Marie Slaughter's blockbuster article in the Atlantic, entitled, "Why Women Still Can't Have It All," detailing the author's struggle with combining a high-powered career in Washington, D.C., and raising two teenage boys. "That really kicked things off for me in terms of thinking about the challenges women still face in the workplace," Mead recalls. At the time, she was a relatively new mom in a senior position at The Motley Fool, so she knew flexibility and family-leave issues were important to her. But Mead also knew those things might not be on the top of the list for women at a different age or stage of their lives and career.

What women want

Figuring out those crucial elements didn't require more books or articles, Mead decided. It required data from women — all women — that detailed what they have, what they want and what they're looking for in an employer. "Those lists of best places to work or best places for women to work just address those specific companies," she says. "But there are thousands of companies out there, and I believe that all of the change that needs to happen should be driven by the women working there." Mead and two colleagues from The Motley Fool — Daniel Stapleton, a user-experience designer, and Adam Hill, a developer — spent nights and weekends during 2014 building the platform. They used that first year to collect data from early adopters — working women in the Bay Area of San Francisco, Boston and New York, where Mead says the conversation about workplace equality was peaking early. "We really used that beta year to make sure we were capturing the right data and to watch how the women were using the site," she explains.

Ursula Mead, co-founder and CEO of InHerSight Source: InHerSight

In early 2015 some local press helped to spread the word, and Mead says they went from having ratings on a few hundred companies to ratings on a few thousand. Within about a month companies such as Ericsson, CEB and Mode Analytics were contacting InHerSight directly, telling Mead what their needs were and asking to better understand their scores and even how to recruit the women that were on the site. "Those early companies really helped guide the further development of the platform," she says. By the end of that year, Mead felt they had enough data and momentum to raise a seed round of financing, with The Motley Fool putting up $995,000 as the lead investor. In early 2016, Mead left The Motley Fool to work on InHerSight as CEO full-time and moved the company to a start-up community called the American Underground in Durham, North Carolina.

The business model

InHerSight makes money by charging companies a fee for listing job openings on the site, starting at $299 for five listings a month. Women who rate companies or use the site to find a job don't pay anything. Mead sees a bigger opportunity down the road for companies to purchase InHerSight's analytics in order to get a better read on what they should be offering women and how they stack up against other companies. "Recruiting and analytics are the two big buckets for revenue that we see going forward," Mead says. While other companies, like Glassdoor and Indeed, also allow users to rate workplaces on a variety of measures, Mead says InHerSight is the only one that looks specifically at the experience of women. A further differentiator, she claims, is the fact that the platform considers only the things that a company can control. "We're not asking, 'Would you recommend this company to a friend?' It's very hard for an employer to have any influence on that," she explains. "We only want to be scoring and measuring companies on things that they can affect and things that can lead to gender equality at work." More from Upstart 25:

The inaugural CNBC Upstart 25: Promising young start-ups

5 start-ups on the path to becoming household names

How David Bowie's former sidekick joined forces with upstart for Oscar victory



Mead is quick to point out, however, that a company that might look good on paper — generous parental leave, for instance — could, in fact, not be so family-friendly if women report that they're pressured to cut their leaves short or don't see a clear path to senior positions. That's why a company such as Amazon can get a fairly high score of 3.5 out of 5 for maternity and adoptee leave, but just a 2.5 when it comes to women's representation in top leadership. Wrote one woman about her experience at Amazon: "Great benefits, excellent parental leave, great people to work with, very diverse. Not a lot of women in leadership roles, though."

Moving the needle