Software engineer, entrepreneur, co-founder of Andreessen Horowitz.
1971–present · Atherton, California
Install Marc's frameworks in Claude Code
/plugin marketplace add adamtpang/summon.guide
/plugin install marc-andreessenInstalls 4 skills from Marc, plus the rest of summon.guide. Source on GitHub.
Marc Andreessen was born July 9, 1971, in Cedar Falls, Iowa, and grew up in New Lisbon, Wisconsin, a town of about a thousand people. He taught himself BASIC on a Radio Shack TRS-80 in elementary school. He enrolled at the University of Illinois at Urbana-Champaign as an undergraduate computer science major, where he worked at the National Center for Supercomputing Applications (NCSA). In 1992–1993, working with Eric Bina, he co-created Mosaic — the first graphical web browser to display images inline with text and to run on common consumer operating systems. Mosaic, more than any other single piece of software, was the moment the World Wide Web became something ordinary people could see and use.
In 1994, fresh out of college, Andreessen partnered with Jim Clark, the founder of Silicon Graphics, to start Mosaic Communications Corporation, soon renamed Netscape Communications. Netscape Navigator became the dominant web browser of the mid-1990s. The company's IPO on August 9, 1995 — the stock opened at $28 and closed at $58.25 the same day, valuing Netscape at $2.9 billion despite having only modest revenue — is widely cited as the catalyst of the dot-com era. After the U.S. v. Microsoft antitrust suit and the bundling of Internet Explorer with Windows crushed Netscape's market share, AOL acquired Netscape in 1999 for $4.2 billion. Andreessen co-founded Loudcloud in 1999 (one of the earliest commercial cloud-services companies); after the dot-com bust, the company pivoted into Opsware and sold to Hewlett-Packard in 2007 for $1.6 billion. In 2009, Andreessen and Ben Horowitz founded Andreessen Horowitz (a16z) on the contrarian thesis that technical founders should be supported as CEOs of their own companies rather than replaced by professional managers. a16z grew into one of the largest venture firms in the world, with notable early investments in Facebook, Coinbase, Airbnb, GitHub, Lyft, Instagram, Skype, Slack, and Stripe.
Andreessen's three signature essays — “Why Software Is Eating the World” (2011), “It's Time to Build” (2020), and “The Techno-Optimist Manifesto” (2023) — have each defined the discourse of their moment. He sits on the board of Meta (since 2008) and has remained one of the most public voices in technology and venture capital, prolific on Twitter / X and on the a16z podcast. He is married to Laura Arrillaga-Andreessen, a Stanford professor and philanthropist; they have one son.
Frameworks distilled from Marc’s life, packaged as Claude Code skills. Each skill is invoked with a slash command and grounded in the primary biographies listed under References.
/marc-andreessen:marc-andreessenSoftware is eating the world. It's time to build. Strong opinions, loosely held. Read the wave you're in and push faster.
Source: Marc's essays at a16z.com (2011–2023)
/marc-andreessen:software-eats-the-worldIdentify the industries where the durable winner will be a software company. The incumbents' advantages are in the wrong currency.
Source: “Why Software Is Eating the World” by Marc Andreessen (WSJ, August 20, 2011)
/marc-andreessen:its-time-to-buildReplace “what's wrong” with “what do we build to fix it, and what is stopping the build?” Bias to action against analysis paralysis.
Source: “It's Time to Build” by Marc Andreessen (a16z.com, April 18, 2020)
/marc-andreessen:techno-optimismTreat capability as the goal. Distrust framings that lower capability under the pretense of safety. Pessimism is fashionable and almost always wrong about technology over a 10-year window.
Source: “The Techno-Optimist Manifesto” by Marc Andreessen (a16z.com, October 16, 2023)
Install in Claude Code
/plugin marketplace add adamtpang/summon.guide
/plugin install marc-andreessenBring Marc’s frameworks into your terminal. One install registers every guide’s skills.
Each Claude Code skill above is grounded in a specific passage of a specific book. These are the primary sources we drew from for Marc.
Marc Andreessen · 2011
The 2011 Wall Street Journal essay that named the era. The argument that software companies were poised to take over industry after industry, framed years before it was conventional wisdom.
Marc Andreessen · 2020
The April 2020 essay written in the early weeks of the pandemic. A direct argument that Western institutions had stopped building, and that the right response to any problem is to ask “what do we build to fix it, and what is stopping the build?”
Marc Andreessen · 2023
The October 2023 manifesto. Marc's most fully articulated worldview: capability over caution, abundance over scarcity, building over critique. The operating philosophy underneath the other two essays.
“Software is eating the world.”
“It's time to build.”
“Strong opinions, loosely held.”
“I'm a relentless optimist about the future.”
“The world will be made of bits and atoms. We need a lot more of both.”
“Every Western institution was unprepared for the coronavirus pandemic… The problem is desire. We need to want these things.”
Their voice on summon.guide is grounded in:
Further reading: en.wikipedia.org/wiki/Marc_Andreessen
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