SAN FRANCISCO — When Pinterest went public in 2019, Christine Martinez’s friends sent congratulations. She had worked closely with the founders of the digital pinboard in its earliest days, and her friends thought she would get rich alongside them.
But as Pinterest’s stock price rose, turning its founders into billionaires, Ms. Martinez realized she would not be compensated or credited for her contributions, she said.
On Monday, she sued.
In a lawsuit filed in Alameda County Superior Court, Ms. Martinez accused Ben Silbermann and Paul Sciarra, two of Pinterest’s three co-founders, of breach of implied contract, idea theft, unjust enrichment and unfair business practices. Ms. Martinez created Pinterest alongside Mr. Silbermann and Mr. Sciarra, the lawsuit said, contributing ideas that were “core organizing concepts,” such as organizing images on boards and enabling e-commerce.
Ms. Martinez, 40, was never formally employed by Pinterest, nor did she ask for a contract. She was not given stock, though she said Pinterest’s founders had verbally agreed to compensate her many times.
Ms. Martinez argued that she and the founders had an implied contract, based on their discussions. Pinterest even named a section of its source code after her, according to the complaint. And she was such close friends with the co-founders that she brought them both home for Christmas and was a bridesmaid in Mr. Silbermann’s wedding.
“I always expected that when they could compensate me, they would,” she said, adding that she had been naïve. “There was never a doubt in my mind.”
Pinterest did not immediately respond to a request for comment.
The lawsuit renews questions about whether Pinterest, which caters primarily to female users, is hostile to women and minorities in its workplace.
Last summer, Ifeoma Ozoma and Aerica Shimizu Banks, two former Pinterest employees, wrote on Twitter about the pay disparities, retaliation and sexist, racist comments they had experienced at the company. Shortly after, Francoise Brougher, Pinterest’s former chief operating officer, sued the company, claiming gender discrimination and retaliation.
In response, Pinterest employees staged a virtual walkout in August last year, demanding that the company increase the number of women and minorities in its top ranks and provide more transparency around promotion levels, retention and pay.
In December, the company agreed to a $22.5 million settlement with Ms. Brougher, including a $2.5 million donation toward charities for women and underrepresented minorities in tech. Pinterest shareholders then sued the company and its board over its workplace culture.
Ms. Ozoma has helped sponsor the Silenced No More Act in California, which will broaden protection of employees who speak out about discrimination or harassment at work. It was recently passed by the State Legislature.
Ms. Martinez said that she was not surprised to see the headlines about Pinterest’s culture and that she had been frustrated by the disconnect between the company’s male founders and its female users.
“I’ve spent a lot of years being really confused about how it is that people believe that these three men created a product like this for women — that they understood women well enough,” she said.
Starting in 2008, the year before Pinterest was founded, Mr. Silbermann and Mr. Sciarra sought Ms. Martinez’s advice on a wide range of concepts, from its name and features to its marketing strategy and product road map, according to the lawsuit.
Ms. Martinez had studied interior design, created a lifestyle blog and founded LAMA Designs, an e-commerce start-up. Even though LAMA’s business model worked and was showing promise, venture capitalists didn’t take her seriously, and she said she had struggled to raise money.
Yet funding for Pinterest, based on little more than an idea and Mr. Silbermann’s and Mr. Sciarra’s credentials, came easier. Ms. Martinez said she was eager to help her friends.
“They had no marketing background or expertise in creating a product for women,” she said. “My role was always to educate them.”
According to the lawsuit, Ms. Martinez gave the co-founders the idea of organizing images on “boards,” a core feature of the site; created its call-to-action phrase, “Pin it”; and established its main categories including home décor, fashion and D.I.Y. She also helped Mr. Silbermann persuade top design and lifestyle bloggers to use Pinterest and promote it. She took him to conferences, gathered feedback from the community and honed the pitch to them, she said.
Ms. Martinez said she realized she would not be compensated only after Pinterest went public in 2019.
Soon after, she said, a death in the family caused her to reflect on her life. That emboldened her to speak up about Pinterest.
“I couldn’t take this to my grave,” she said.