In January 2017, TechCrunch reported that Newmark donated $500,000 to Wikipedia's attempt at "reducing harassment and vandalism on the site and improve the tools moderators use every day to keep the peace."
Through Craig Newmark Philanthropies, Newmark has contributed more than $40 million to journalism initiatives since 2015. In 2017, he donated $1 million each to ProPublica and the Poynter Institute. He made a $20 million endowment to the CUNY Graduate School of Journalism, which was subsequently renamed the Craig Newmark Graduate School of Journalism. Newmark also has a private charitable foundation, to which he contributed $50 million in 2016. Newmark's foundation supports military families, voter registration efforts, and women in technology. In 2018 Newmark's donations totaled $143 million. In 2019, he donated $6 million to Consumer Reports to fund a Digital Lab focused on consumer privacy rights and digital security.
In May 2017, Forbes estimated that Newmark's net worth is at least $1.3 billion based on his ownership of at least 42% of Craigslist. He called a prior $400 million Forbes estimate of his net worth "bogus." In an interview published in 2017 he said that "By monetizing Craigslist the way I did in 1999, I probably gave away already 90 percent or more of my potential net worth." Newmark has described his business philosophy as "minimal profit" rather than non profit: "Basically I just decided on a different business model in '99, nothing altruistic. While Silicon Valley VCs and bankers were telling me I should become a billionaire, I decided no one needs to be a billionaire — you should know when enough is enough. So I decided on a minimal business model, and that's worked out pretty well. This means I can give away tremendous amounts of money to the nonprofits I believe in."