In December 2025, Andrej Karpathy said 80 percent of his code was generated by AI agents, a figure he described as arriving at what he called "the inflection point for agentic coding." It was less than a year after he coined the phrase "vibe coding" and within months he was declaring that concept passe. The 18-month arc, from casual AI prompting to what he now calls agentic engineering, is the clearest public account yet of where professional software development is heading.
The tweet that named a generation of programming
In February 2025, Karpathy posted on X that he had started to "fully give in to the vibes, embrace exponentials, and forget that the code even exists." The phrase named a practice that had no common label yet: accepting AI-generated code without close scrutiny, iterating by pasting error messages back into a chat window, building fast without studying the underlying implementation. He called it vibe coding. The term spread within days and had entered investor memos and style guides before the month ended.
This was not Karpathy's first time labelling a shift. In November 2017, he published "Software 2.0" on Medium, arguing that neural networks represented a new programming substrate: instead of writing explicit instructions, developers would define desired behavior and let optimization find the implementation. In September 2023, he extended the frame on X, describing large language models not as chatbots but as "the kernel process of a new Operating System", with the context window as RAM and agents as long-running processes. Each label arrived before the market had named the thing it described, and each one compressed the timeline to the next.
StartupHub.ai data shows 602 AI developer tools companies now tracked in our database, a category that barely existed in those terms when Karpathy wrote "Software 2.0." Of the 41 with disclosed funding stages, 20 (49 percent) remain at Seed, consistent with Karpathy's observation that the vibe-coding phase was real but unstructured: demand outpaced tooling discipline.
December 2025: the inflection point Karpathy named
The 80 percent figure was not a projection. Karpathy stated it as a description of his actual December 2025 workflow and later identified that month as a qualitative turning point for agentic coding. Agent-generated code chunks had become large enough, and coherent enough, that the practical question shifted from whether the agent could handle a task to how to verify its output at the scale he was now delegating. He noted at the time that he could not recall the last occasion when he had manually corrected the model's direction mid-task.