Unveiling Y Combinator's Fall 2025: The AI-Powered Startups Shaping Tomorrow

Since 2005, Y Combinator has backed over 5,000 companies with a combined valuation of over $800 billion. The Fall 2025 batch features around 150 startups spanning diverse industries, with a clear trend: B2B software dominates, making up nearly two-thirds of the cohort. This signals a focus on building infrastructure and tools for other businesses. Beyond B2B, the batch includes consumer startups, healthcare, industrials, fintech, and real estate, reflecting YC's shift toward practical, revenue-driven innovation. These founders are building the rails for the AI era—not just riding it.

The Builders

Who are these ambitious founders disrupting innovation?

• Multifactor: Zero-trust authentication, authorization, and auditing for AI agents. AI agents are moving faster than security can keep up, and Multifactor provides enterprise-grade protection to prevent exploits like the "invitation is all you need" Gemini breach.

• Lightberry: The social brain for robots. It gives humanoids the ability to see, hear, talk, and move like humans, transforming remote-controlled machines into autonomous teammates.

• Metorial: Vercel for MCP. It makes MCP enterprise-ready in minutes with reliability, security, and scale built in, enabling startups and enterprises to scale AI agents globally in days.

• Unsiloed AI: APIs for unstructured data. It turns messy, multimodal data into structured formats that LLMs and AI agents can understand, addressing the 40% of time AI teams spend on data cleanup.

• Hyperspell: Memory for AI agents. It unifies context from tools like Gmail, Slack, Notion, and Drive, allowing agents to recall, reason, and remember across company knowledge.

• Bear: Marketing for AI Search. It helps brands get discovered inside AI search results as blue links fade and ChatGPT becomes the new Google, ensuring visibility where decisions happen.

• Dome: Unified API for prediction markets. It provides a single API for trading across platforms like Polymarket and Kalshi, connecting data, liquidity, and tooling into one ecosystem.

• Hypercubic: AI to maintain and modernize COBOL/mainframes. It addresses the risk of legacy code in banks and airlines by using AI to reason about complex software safely.

• Parrot: TikTok for language learning. It turns short-form video into real language acquisition, using context and repetition for fluency instead of traditional drills.

• Boom AI: Your AI growth team for e-commerce brands. It personalizes interactions at internet scale to turn lost visitors into loyal buyers, cutting acquisition costs.

• Everest: AI support engineers for outsourced IT services (MSPs). It enables MSPs to deliver proactive support and improve margins by automating repetitive IT work.

• Telemetron: Customer support platform built for hardware. It uses LLMs to reason across logs, manuals, and live data for intelligent hardware support in EVs, wearables, and robotics.

• Narrative: Infrastructure for AI video processing. It builds tools to make video-native AI agents a reality, overcoming challenges in video understanding.

• Deeptrace: AI agents for on-call. It automates the end-to-end on-call workflow, from alert triage to resolution, reducing noise and improving efficiency.

• Digipals: Building the future of social in the age of AI. It reimagines connection with an AI-native group chat that helps coordinate hangouts and stay connected through real-life context.

• Aside: Real-time answers for sales calls. It provides AI that retrieves the right answer live during conversations, boosting confidence and conversion rates.

• Nucleo: Automated CT scan analysis for oncology care. It helps oncologists extract insights from CT scans for tumor characterization and treatment, working with top hospitals.

• Jarmin: 24/7 Machine Learning Engineer employees. It acts as a hireable ML engineer that handles AI/ML work through simple conversation.

• Caddy: Control all your work apps with your voice. It eliminates clicks and copy-paste chaos by allowing knowledge workers to talk to their computers for faster task completion.

• Lemma: Continuous learning for AI agents. It detects and fixes failures in production automatically, based on Stanford research, ensuring agents learn over time.

• Clad Labs: The brainrot IDE. It integrates gaming and scrolling into the AI coding loop, subsidized by ads and affiliate revenue, making it a Gen Z-native coding tool.

The Stories Behind the Builders

Every founder's journey is unique, driven by personal pain points or unexpected insights. These teams come from diverse backgrounds, representing bold and resourceful innovation.

• Dome's founders, Kurush Dubash and Kunal Roy, started after losing money trading prediction markets and built the tools they wished existed.

• Parrot's founders turned a co-founder's failed attempt to impress a girl while learning Spanish into a breakthrough in language learning. As Julia Hudea explained, "Erik, our co-founder, started learning Spanish to impress a girl on vacation and accidentally fell into a year-long rabbit hole on how polyglots learn languages - emerging fluent in three. We did a deep dive on every language learning tool and realized none teach the way humans naturally learn."

• Lightberry's team, inspired by sci-fi robots like R2-D2 and WALL·E, aims to make robots coworkers and companions. Founders Ali Attar and Stephan Koenigstorfer said, "We want robots to be coworkers and companions, not just tools."

• Lemma's founders, Jerry Zhang and Cole Gawin, have been best friends since freshman year and are obsessed with agent systems. They stated, "We're young, scrappy, and will do whatever it takes to make things work."

• Telemetron's Shivani Patel is driven by a hardware obsession, excited about physical products people can hold.

• Aside's Jun Kim met his co-founders in high school, where one launched a Microsoft-backed nonprofit and another built a successful app solo.

• Hyperspell's Manu Ebert has been building chatbots since age 13 and combined neuroscience research with machine learning to address AI agent memory.

• Boom's founders, including Juan Casian, Sergio Garcia, and Jose Toscano, have over a decade of experience building and scaling companies, learning from cash crises and team rebuilds to create a platform for business growth.

Across the batch, founders operate with relentless drive, moving faster than expected and rejecting limitations.

The YC Effect

YC accelerates growth and rewires how founders think, build, and dream, fundamentally changing company trajectories.

• Pace and intensity: Aman Mishra of Unsiloed AI said, "YC compresses months of growth into weeks. The real magic is momentum—you leave with a completely new sense of how fast 'fast' can be."

• Clarity and focus: Jun Kim noted, "The environment forces clarity through competition. Everything moves faster, focus gets sharper, and suddenly everything you do is leveraged 10x." Yolanda Cao of Everest emphasized, "Focus. YC forces focus on what drives our main KPI, and nothing else."

• User insights: Connor Waslo of Caddy shared how user conversations revealed the real problem: "People just want to get work done faster."

• Ambition and community: Karim Rahme of Metorial explained, "You are the average of the five people you spend the most time with. At YC, those five are the most ambitious founders you'll ever meet." Vivek Nair of Multifactor turned down VC offers for YC, citing distribution advantages.

• Mindset shift: Janak Sunil of Bear said, "At the beginning of the batch, we used to think practically and cautiously; now, we think nothing but big." Sai Gurrapu of Hypercubic added, "YC helps you form clarity. It strips away the noise and forces you to focus on building something people desperately need. Move and fail fast, talk to users, build the inevitable."

The YC effect is about thinking bigger, moving with conviction, and being surrounded by innovators.

The Fall 2025 batch marks a turning point for YC and the startup world. Founders are building infrastructure for the AI economy, from unstructured data to humanoid intelligence. Innovation is about execution, speed, and relentless ambition. If this batch is any indicator, the next generation of billion-dollar companies will define AI.