Y Combinator

Counter-Swarm Defense

An incident involving Iranian drone swarms exposing the cost asymmetry and fragmentation of current defense systems has prompted Y Combinator to solicit counter-swarm stack solutions. These new initiatives aim to replace traditional interceptor models with software-driven, non-kinetic technologies capable of neutralizing thousands of coordinated units through sensor fusion and autonomy targeting. The resulting infrastructure is expected to function more like scalable cloud networks than conventional weaponry, fundamentally shifting the defense paradigm from weapon operation to distributed system management.

Company Brain

Enterprise AI automation is currently bottlenecked by the fragmentation of proprietary domain knowledge siloed within human memory and legacy systems, creating an urgent need for a "company brain" that extracts, structures, and converts this data into executable skills files. This dynamic infrastructure serves as a critical intermediate layer between raw enterprise data and reliable AI agents, moving beyond simple document chatbots to map specific operational workflows like refund handling and incident response. The speaker predicts universal global adoption of this technology for safe, efficient automation and invites startups to apply to Y Combinator to build this essential primitive.

AI-Personalized Medicine

Intelligent agents are deploying personalized health data and falling production costs for genetic medicines to generate precise clinical suggestions and bespoke treatments. This convergence of regulatory openness and declining diagnostic expenses is enabling the early detection of disease signals while allowing patient access to specialized trials. Industry leaders anticipate this shift will democratize access to severe illness care and spur a surge in startups building the necessary infrastructure for this new model.

AI-Native Service Companies

Driven by the rapid evolution of AI models from software tools to autonomous professional agents, the market is shifting toward "AI-native" companies that sell direct services rather than software licenses. This investment thesis targets high-spend sectors like insurance, accounting, and healthcare administration where global spending on services vastly exceeds software costs and outsourcing rates are already high. To capitalize on this shift, a specific call for submissions has been issued to founders building "place as a service" ventures that embed human professionals within their AI-driven delivery models.

Replit's CEO On The Only Two Jobs Left In The Company Of The Future

Amjad Masad, Andrew Miklas

Replit recently secured $400 million in Series D funding to achieve a $9 billion valuation while executing a strategic pivot toward "AI-native developers" who build software through natural language interactions with their Agent 4 system. By abstracting traditional coding behind multimodal AI agents, the platform enables non-engineers to rapidly deploy applications and reduce development costs by up to 70%, effectively shifting the company's focus from technical setup to high-level business orchestration. This product-led growth model empowers a diverse range of users, from solo entrepreneurs to enterprise teams, to accelerate idea velocity and build internal tools without requiring deep programming expertise or large engineering budgets.

How To Build A Company With AI From The Ground Up

Diana Hu

This presentation argues that AI must function as a company's central operating system rather than a peripheral tool, driving a shift toward closed-loop systems that render the entire organization queryable for automated decision-making. In this model, traditional middle-management hierarchies are eliminated and replaced by AI agents that execute engineering tasks and manage workflows, allowing human leaders to focus on strategy as founders, builders, or directly responsible individuals. By leveraging these "AI software factories," startups gain a decisive advantage over incumbents to achieve tenfold velocity increases and operate with human headcount replaced by optimized token usage.

How to Make Claude Code Your AI Engineering Team

Garry Tan, Gary

Gary Tan, President and CEO of Y Combinator, has launched GStack, an open-source framework that restructures AI coding assistants into specialized engineering teams to overcome current limitations in model scaffolding. The system utilizes skills like Adversarial Review and the Office Hours query to automatically identify design flaws, generate multiple UI variants, and process hundreds of daily pull requests without traditional to-do lists. With over 70,000 GitHub stars, GStack shifts developer focus from manual coding to strategic oversight, enabling the management of parallel AI sessions to accelerate software factory operations from ideation to production.

How Stripe Built Their New Website

Aaron Epstein, Katie Dill

Over a year in the making, Stripe's comprehensive homepage redesign repositioned the company as a global financial infrastructure leader by replacing visual fatigue with a dynamic bento-grid layout and a manifesto-style narrative. The project leveraged AI tools to accelerate asset creation while maintaining rigorous human oversight to ensure the "billionth" transaction scale and live economic metrics conveyed trust to diverse user segments. By prioritizing progressive disclosure and intentional motion over traditional scrolling, the team successfully clarified value propositions ranging from micro-entrepreneurs to the 78% of Forbes AI 50 companies that now rely on the platform.

BillionToOne Is Solving One of Biotech’s Hardest Problems

Jared Friedman, David Tsao, Oguzhan Atay

Billion to One, founded by PhD students Oguzhan and David, leverages proprietary synthetic DNA methods to detect rare cell-free DNA variations for prenatal screening and cancer liquid biopsies. Since its public listing with a valuation over $4 billion, the company has scaled its automated facility to process 600,000 tests annually and launched North Star Select for late-stage cancer treatment guidance. The firm now executes a strategic roadmap to address early-stage cancers through a capital-efficient progression from commercial adoption to population-wide screening, aiming to significantly reduce cancer mortality rates.

This Startup Catches Fraud at Scale

Jared Friedman, Karine Mellata

Variance has officially exited stealth mode following a $21 million Series A round to commercialize AI agents that automate trust and safety infrastructure for Fortune 500 clients like GoFundMe and IAC. Founded by ex-Apple engineers Karine and Michael, the 12-person team leverages a unique "agentic" architecture to solve complex unstructured data problems in fraud detection and compliance without manual rule updates. Despite a 2024 leadership injury that threatened operations, the company is scaling its full-stack decisioning platform to replace traditional human review workflows with adaptive, self-healing systems designed to trace sophisticated abuse graphs.

" It is very possible that the first people to live to a thousand are alive right now."

Max Hodak

Technological accelerations in artificial intelligence and brain-computer interfaces are driving a paradigm shift where the first individuals capable of living to 1,000 years may already exist. By 2035, widespread AI accessibility and new lateral treatments will reframe the human condition despite market undervaluation and low public awareness. These advancements will fundamentally reconfigure human interaction by creating functional equivalents to direct brain-to-brain communication.

Differences Between The Leading AI Models

Madhav Jha

Current AI models operate as specialized tools where Opus functions as a general workhorse, Codex excels in back-end debugging, and Gemini leads in front-end applications. Within three to six months, the market is expected to shift toward commoditization driven by converging model behaviors and narrowing gaps between open-source and proprietary options. Strategic success will therefore depend on building a user-centric layer that leverages these unique capabilities to optimize the customer journey rather than relying on raw model differentiation.

This Is The Holy Grail Of AI

Ian Fischer

Poetic is advancing a recursively self-improving AI system that autonomously enhances its own intelligence at a fraction of the cost and time required by major competitors like Anthropic, OpenAI, and Google. Unlike industry standards that demand hundreds of millions of dollars and months of effort to train new Large Language Models from scratch, Poetic's proprietary method accelerates these cycles significantly. This speed and efficiency advantage allows Poetic to potentially outpace rivals who remain constrained by the prohibitive expenses and long timelines of traditional retraining approaches.

AI Is Unlocking Millions Of New Builders

Mukund, Madhav Jha

Led by twins Mukund and Madhav Jar, Emergent is a YC Summer 2024-funded platform that empowers non-technical users to generate production-ready software through AI agents, having already built seven million apps across 190 countries. The company differentiates itself by utilizing a custom Kubernetes infrastructure and multi-agent architecture to solve the "it works on my machine" problem, while its core team achieved top-tier status on the SWE-bench benchmark within two months. By pivoting from automated testing to full-stack application development, Emergent has democratized software creation, allowing solopreneurs to launch functional products for thousands of dollars instead of the traditional half-million-dollar cost.

Startup School is coming to India! 🇮🇳

Harshil Mathur, Vidit Aatrey, Lalit Keshre, Mukund Jha

Y Combinator is hosting its inaugural one-day Startup School in Bangalore on April 18th to connect the next generation of Indian founders with industry leaders. The event convenes prominent founders from YC-backed companies such as Razorpay, Meesho, Grow, and Emergent to discuss the latest developments in technology and startups. This gathering aims to foster a community among top Indian builders and hackers by facilitating direct engagement with successful entrepreneurs.