Many older, established companies are already in the habit of making sure theyre not discriminating against women when it comes to pay. Now tech startups are starting to get hip to the practice, too.

Pinterest is joining a growing group of young tech startups that are closely reviewing employees salaries to make sure men and women are paid fairly. An outside firm is analyzing pay at the 5-year-old social network to make sure its not discriminating against any particular group, a spokeswoman recently told The Huffington Post.

The reviews, which started about 18 months ago, take place during the times of year when employees are up for bonuses and promotion, said spokeswoman Malorie Lucich in an email. The company, which has more than 600 employees, wouldnt say if anyone has gotten a raise as a result of its analysis or whether it had turned up any bias.

Pay audits are gaining steam quickly in part because of the growing focus on the struggles of women in the tech industry -- there are fewer females in general, and a real dearth in high-profile positions. The idea is also catching on as so many of these startups start to, well, grow up.

At first a startup is so focused on survival, and so convinced of its own idealism and its own rightness, who could possibly think we could have biases, Glenn Kelman, chief executive of 10-year-old real estate website Redfin, told HuffPost.

At the prompting of a couple of its female employees, Redfin not only took a companywide look this year at how it pays women and men, it also published the results. The data happened to look pretty good -- pay is about equal for men and women at the 1,000-person company. In some cases, women are pulling in more money. That surprised Kelman, who cautioned that he expects that might not always be the case. "We're going to make mistakes," he said. The key is having a system for catching discrimination and quickly fixing it.