August 6, 2025
5 min read
Lee Chong Ming
Vercel's CEO says AI agents are becoming software’s next users, transforming how APIs and developer tools are designed and built.
An Accel-backed startup CEO says your next user isn't human — and it's changing how software gets built
Vercel's CEO, Guillermo Rauch, believes the future of software development is shifting from building for human users to building for AI agents. "Your customer is no longer the developer," Rauch explained on the "Sequoia Capital" podcast. "Your customer is the agent that the developer or non-developer is wielding." Vercel, a web infrastructure startup valued at $3.25 billion in 2024, is witnessing this shift firsthand. Rauch emphasized that code is increasingly written not just for humans to read or interact with, but for AI agents to understand, use, and extend."That is actually a pretty significant change," Rauch said. "Is there something that I could change about that API that actually favors the LLM being the, quote-unquote, entity or user of this API?"This AI-first era demands that software tools evolve based on how large language models (LLMs) interact with them. Rauch noted:
"LLMs' strengths and weaknesses will inform the development of runtimes, languages, type checkers, and frameworks of the future."He also highlighted that Vercel's newer users include not only developers but also designers, marketers, and even AI agents. These users expect seamless functionality.
"Developers were used to dealing with errors and terrible, negative feedback all day long," Rauch said. "But today's users have a much shorter fuse when something goes wrong."Still, Rauch views this as positive pressure for product builders, aiming for software that "works 99.99% of the time." Last year, Vercel raised $250 million in a Series E round led by Accel, with participation from Tiger Global and GV.
Rise of AI agents
The year 2025 has been marked as the rise of AI agents, which could fundamentally change how the internet and software interact with users. Bernstein analysts wrote in February that while websites and apps will remain, users may no longer interact with them directly. Instead, AI assistants will aggregate information, content, and widgets, becoming "the aggregator of the aggregators.""If it scales and plays out like we think it might, this. Changes. Everything. The aggregators get disaggregated, and much of consumer internet may be structural shorts. Welcome to the Agentic AI era," the analysts wrote.However, AI agents are not without flaws. Researchers warn that errors compound with each step an agent takes. Patronus AI, a startup helping companies optimize AI technology, explained:
"An error at any step can derail the entire task. The more steps involved, the higher the chance something goes wrong by the end."Their statistical model showed that an agent with a 1% error rate per step could have a 63% chance of error by the 100th step. Despite these challenges, guardrails such as filters, rules, and tools to identify and remove inaccurate content can mitigate error rates. Small improvements can lead to significant reductions in overall error probability.
Source: Originally published at Business Insider on August 6, 2025.