CEO OS
People ·April 12, 2026 ·person

Marc Andreessen

Who they are

Marc Andreessen co-wrote Mosaic, the first widely-used web browser, co-founded Netscape, and then co-founded Andreessen Horowitz — one of the most influential venture firms in Silicon Valley. Known for "Software is eating the world" and, more recently, for his aggressive public advocacy of technology and growth. For a founder-CEO, his most useful contribution is still the simplest one: product-market fit is the only thing that matters, and everything else is downstream of it.

Core Ideas

  • Product-market fit is the only thing that matters — the rest is optimization
  • Software is eating the world — most industries will be reshaped by software
  • The only two jobs of a startup CEO: don't run out of money, and find product-market fit
  • Jeff Bezos — both are long-horizon operators, different temperament
  • Keith Rabois — same PayPal/early-web Silicon Valley generation

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