Mozilla co-founder Brendan Eich resigned just two weeks after being named chief executive when a Twitter rampage rose up against the appointment.
Anger focused on Eich's $1,000 donation to Prop 8, California's 2008 campaign to ban same-sex marriage in the state.
"I'm an employee of @mozilla and I'm asking @brendaneich to step down as CEO," Chris McAvoy, head of Mozilla's Open Badges project, tweeted Thursday.
Mozilla executives insist that Eich stepped down of his own accord.
Three other board members quit over the controversy, while the dating site OKCupid asked members to boycott Firefox, the company's web browser.
Eich responded by emphasizing the diversity he cited as integral to the company's success.
"I am committed to ensuring that Mozilla is, and will remain, a place that includes and supports everyone, regardless of sexual orientation, gender identity, age, race, ethnicity, economic status, or religion," he posted on his blog.
Geoffrey MacDougall, the head of development for Mozilla, defended Eich.
"The free speech argument is that we have no right to force anyone to think anything," he wrote in a blog post. "We have no right to prevent people from pursuing their lives based on their beliefs."
Andrew Sullivan, a prominent gay writer and advocate for legalizing same-sex marriage, surprised many when he spoke out in outrage over Eich's departure.
"If this is the gay rights movement today - hounding our opponents with a fanaticism more like the religious right than anyone else - then count me out," Sullivan wrote.
Eich refused to withdraw his donation to Proposition 8, a bill that was later overturned in 2013, though he apologized for hurting anyone's feelings.
"Without getting into my personal beliefs, which I separate from my Mozilla work -- when people learned of the donation, they felt pain. I saw that in friends' eyes, [friends] who are LGBT [lesbian, gay, bisexual, or transgendered]. I am sorry for causing that pain," Eich told CNET.
