Marc Andreessen, born July 9, 1971, is an American entrepreneur, investor, and software engineer. He gained prominence as the co-author of Mosaic, the first widely used web browser with inline images, which significantly contributed to the popularization of the Internet. Subsequently, he co-founded Netscape Communications, further commercializing web browsing. Andreessen is also the co-founder and general partner of the venture capital firm Andreessen Horowitz (a16z).
Andreessen's career includes co-founding and later selling Opsware (formerly Loudcloud) to Hewlett-Packard, and co-founding Ning, a platform for social networking websites. He has invested in numerous successful tech companies, including Facebook, Twitter, and LinkedIn. At Andreessen Horowitz, which he co-founded in 2009, he invests in both early-stage startups and established growth companies across various industries, including healthcare, consumer, crypto, gaming, fintech, education, and enterprise software. As of July 2025, Andreessen Horowitz ranks first among venture capital firms by assets under management, with US$46 billion. In January 2026, Andreessen discussed AI's potential, market dynamics, and policy on the a16z podcast. In 2024, he became an advisor to Donald Trump. His net worth is estimated at $1.9 billion as of January 2025.
