Karpathy: Software Is Changing, Again (Software 3.0)

Why it matters

Andrej Karpathy — OpenAI founding member and former Tesla AI director — is the clearest explainer of large models working today. In this June 2025 talk at YC's AI Startup School he frames 'Software 3.0': Software 1.0 is code, 2.0 is neural-net weights, and 3.0 is programming LLMs in natural language. With metaphors like 'LLMs are the new operating system' and 'partial-autonomy products', he lays out how software should be designed in the AI era. If you build AI products, these 40 minutes are the best-spent 40 minutes right now.

Key takeaways

• Three paradigms of software: 1.0 write code, 2.0 tune weights, 3.0 write prompts in English — the prompt is the new program.
• LLMs are like early mainframe operating systems: expensive compute, centrally hosted, time-shared — we live in 'the 1960s of AI'.
• LLM 'psychology': a people-simulator trained on all human text, with superhuman memory but also hallucinations and forgetfulness.
• Great products are 'partially autonomous': AI generates, humans verify — minimize verification cost and give users an autonomy slider.
• Everyone can program now — the biggest opportunity is letting non-programmers build software in natural language (vibe coding).