With the release of new AI models that are better at coding, developers are increasingly using AI to generate code. One of the newest examples is the current batch of Y Combinator, the storied Silicon Valley startup accelerator. A quarter of the W25 startup batch have 95% of their codebases generated by AI, YC managing partner Jared Friedman said during a conversation posted on YouTube.

Friedman said that this 95% figure didn’t include things like code written to import libraries but took into consideration the code typed by humans as compared to AI.

“It’s not like we funded a bunch of non-technical founders. Every one of these people is highly technical, completely capable of building their own products from scratch. A year ago, they would have built their product from scratch — but now 95% of it is built by an AI,” he said.

In a video titled “Vibe Coding is the Future”, Friedman, along with YC CEO Garry Tan, managing partner Harj Taggar, and general partner Diana Hu, discussed the trend of using natural language and instincts to create code.

Last month, former head of AI at Tesla and ex-researcher at OpenAI, Andrej Karpathy described the term “vibe coding” to describe a way to code using large language models (LLMs) without focusing on code itself.

Code generated from AI is far from perfect, through. Studies and reports have observed that some AI-generated code can insert security flaws in applications, cause outages, or make mistakes, forcing devs to change the code or debug heavily.

During the discussion, Hu said that even if product builders rely heavily on AI, one skill they would have to be good at is reading the code and finding bugs.

“You have to have the taste and enough training to know that an LLM is spitting bad stuff or good stuff. In order to do good ‘vibe coding’, you still need to have taste and knowledge to judge good vs bad,” she said.

Tan also agreed on the point of founders needing classical coding training to sustain products in the long run.

“Let’s say a startup with 95% AI-generated code goes out [in the market], and a year or two out, they have 100 million users on that product, does it fall over or not? The first versions of reasoning models are not good at debugging. So you have to go in depth of what’s happening with the product,” he suggested.

VCs and developers have been excited about AI-powered coding. Startups including Bolt.new, Codeium, Cursor, Lovable, and Magic have raised hundreds of millions of dollars in funding in the last 12 months.

“This isn’t a fad. This isn’t going away. This is the dominant way to code. And if you are not doing it, you might just be left behind,” Tan added.