Engineering, Product and Design Startups funded by Y Combinator (YC) in the San Francisco Bay Area 2025

Scale accelerates the development of AI within organizations of any size to deliver critical business insights and operational efficiency. Its data-centric infrastructure platform leverages RLHF (Reinforced Learning with Human Feedback) to help organizations build the strongest AI models that supercharge their business, with customers across industries including Meta, Microsoft, U.S. Army, DoD’s Defense Innovation Unit, Open AI, General Motors, Toyota Research Institute, Brex, Instacart and Flexport.

GitLab is the first single application for the entire DevOps lifecycle. Only GitLab enables Concurrent DevOps, unlocking organizations from the constraints of today’s toolchain. GitLab provides unmatched visibility, radical new levels of efficiency and comprehensive governance to significantly compress the time between planning a change and monitoring its effect. This makes the software lifecycle 200% faster, radically improving the speed of business. GitLab and Concurrent DevOps collapses cycle times by driving higher efficiency across all stages of the software development lifecycle. For the first time, Product, Development, QA, Security, and Operations teams can work concurrently in a single application. There’s no need to integrate and synchronize tools, or waste time waiting for handoffs. Everyone contributes to a single conversation, instead of managing multiple threads across disparate tools. And only GitLab gives teams complete visibility across the lifecycle with a single, trusted source of data to simplify troubleshooting and drive accountability. All activity is governed by consistent controls, making security and compliance first-class citizens instead of an afterthought. Built on Open Source, GitLab leverages the community contributions of thousands of developers and millions of users to continuously deliver new DevOps innovations. More than 100,000 organizations from startups to global enterprise organizations, including Ticketmaster, Jaguar Land Rover, NASDAQ, Dish Network and Comcast trust GitLab to deliver great software at new speeds.

Our mission is to make every search interaction meaningful & rewarding, through developer-friendly and enterprise-grade APIs. Algolia is the leading Search & Discovery API for websites and mobile apps. We help the most innovative companies across e-commerce, media and SaaS industries create powerful, relevant and scalable discovery experiences for their users. Unlike other solutions, our hosted platform reduces the complexities of building and scaling a fast, relevant digital experience and helps teams accelerate development time. More than 9,000 companies like Under Armour, Twitch, Periscope, Medium and Stripe rely on Algolia to manage 50+ billion search queries a month. Founded in 2012, we're backed by $184M in funding from Accel Partners, Alven Capital, Point Nine Capital and Storm Ventures. The team is headquartered in San Francisco with offices in Paris, London, New York, and Atlanta. To learn more, visit www.algolia.com. --- We’re looking for talented, passionate people to build the world’s best search technology. As an ownership-driven company, we seek team members who thrive under autonomy and diversity. We're committed to building an inclusive and diverse workplace. We care about each other and the world around us, and embrace talented people regardless of their race, age, ancestry, religion, sex, gender identity, sexual orientation, marital status, color, veteran status, disability and socioeconomic background

PagerDuty is an operations performance platform delivering visibility and actionable intelligence across the entire incident lifecycle. Their SaaS-based solution empowers over 10,000 small, mid-size and enterprise global customers such as Comcast, eHarmony, Slack and Lululemon with the insight to intelligently respond to critical disruptions for exceptional customer experience. PagerDuty was founded to deliver a new and innovative approach to increase business response and efficiency. When brand reputation depends on customer satisfaction, PagerDuty arms businesses with the insight to proactively manage incidents and events that may impact customers across their IT environment.

At Optimizely, we're on a mission to help people unlock their digital potential. We do that by reinventing how marketing and product teams work to create and optimize digital experiences across all channels. With Optimizely One, our industry-first operating system for marketers, we offer teams flexibility and choice to build their stack their way with our fully SaaS, fully decoupled, and highly composable solution. We help companies around the world orchestrate their entire content lifecycle, monetize every digital experience and experiment across all customer touchpoints – all through Optimizely One, the leading digital experience platform that powers every phase of the marketing lifecycle through a single, AI-accelerated workflow. Optimizely has nearly 1500 employees across our 21 global offices and has 700+ partners. We are proud to help more than 10,000 businesses, including H&M, PayPal, Zoom, and Toyota, enrich their customer lifetime value, increase revenue and grow their brands. At Optimizely, we live each day with a simple philosophy: large enough to serve, small enough to care. Learn more at optimizely.com.

We'd like to automate monitoring. To advance that mission, we're building Sonarly. Coding agents are amazingly good at building software. But they struggle fixing production bugs because they lack the right context for them. We give them that context, eliminating the time you spend on bug detection, session replay, issue description, and endlessly copy-pasting logs to your AI agent.

As autonomy moves into complex safety-critical domains (e.g., aviation), failures become more costly and companies must devote significant in-house effort to validate their system before real-world deployment. Valgo accelerates autonomous systems development and certification by providing tooling to perform algorithmic safety validation at scale. We are building a platform to efficiently find rare and realistic failure events in simulation at a fraction of the compute cost required by existing approaches. Our tools are agnostic to models/simulators (i.e., black box) and can be applied across industries such as autonomous vehicles, aviation, robotics, space, defense, energy, and finance. Valgo was founded by Stanford PhDs who wrote the textbook and taught the course at Stanford on algorithmic safety validation. We also have significant industry experience working on an FAA-certified collision avoidance system at MIT Lincoln Laboratory, validating autonomous aircraft at Xwing, and collaborating with industry sponsors across transportation, aviation, and energy.

AtlasGrid automatically builds a visual graph of your mobile app UI and displays analytics directly on your screens. Additionally, our fleet of AI-powered agents will continuously analyze thousands of mobile apps, gathering design insights and identifying growth opportunities + actionable product improvements.

Inspector helps front-end engineers ship faster with AI by automating the most frustrating part of the job — gathering context between the browser and the codebase. Inspector is an AI IDE for front-end that connects your browser and codebase. Inspector lets you select elements visually and prompt changes, giving coding agents access to the same runtime context developers have: visuals, elements, and logs. With Inspector, you’re editing right in the front-end, not buried under tabs and screenshots.

Lemma enables AI agents to continuously improve from user feedback and production outcomes. Instead of relying on manual prompt tuning and reactive debugging, Lemma detects when an agent’s performance drifts, pinpoints the exact step causing failures, generates optimized prompt candidates, and automatically delivers improvements through our API or by opening a pull request in your codebase. Built by ex-AI engineers who felt this pain firsthand, Lemma turns static agents into self-improving systems, helping teams ship reliable AI products faster with compounding performance gains over time. Deploy 1x. Learn forever.

Rovr streamlines engineering operations by automating intake, triage, routing, and cross-team coordination. It replaces internal forms, manual Slack triage, and scattered docs with an AI front desk that understands requests, assigns owners, updates context, and posts status changes directly into Slack. Rovr’s built-in ops CRM gives teams a single system of record for eng requests — from tooling access to platform incidents to dev-infra workflows — reducing operational drag across the entire org.

We are building Siri for work, but it actually works. Caddy turns your voice into the next computing interface. It understands what’s on your screen and your intent, so work gets done while you stay in flow. Say “create a Linear ticket and share it to Slack” and Caddy handles it instantly in the background. Caddy’s founders previously led product and design for Loom’s AI suite and core products. We believe the next era of computing will be powered by voice, where computers understand what you say and what’s on your screen so work happens naturally.

Semiotic is an AI-native design firm. We’re starting with designing landing pages for fast‑growing startups. Existing AI website builders didn't make creating websites easier—they made creating ugly websites easier. So, companies choose between blue-purple gradient slop or agencies with 3-month waitlists and $100k minimums. You don't have to choose anymore. Start a project: semiotic.so

Compyle is a less autonomous coding agent that asks before it acts. We're like Cursor or Claude Code - but you won't need to rewrite your codebase every time you use it for more than a small task. We built Compyle because we were frustrated with the direction other coding agents are headed. They're all racing to be more autonomous, running for hours without human input. This doesn't work for real production code. When agents run autonomously, they make countless small decisions that pile up in your codebase. Engineers lose ownership - they don't know what was implemented, can't effectively debug or maintain it, and struggle to build on top of it. The code becomes a black box, and they're forced to throw it away. Compyle keeps engineers in the driver's seat.

Ship reliable agents with confidence. AI agents often fail quietly, picking the wrong tools, looping, hallucinating, and more. The Context Company tells developers when and exactly where their agents fail so issues can be uncovered and fixed fast. It combines traditional observability across traces, tool calls, latency, and costs with the ability to uncover silent failures that standard monitoring misses. Get started with less than 10 lines of code.

Sourcebot is an open source code understanding platform for massive codebases. We’re used by thousands of engineers in some of the largest companies in the world, including NVIDIA, Red Hat, Wikimedia, and Arista Networks. Understanding code, not writing it, is the primary bottleneck for large engineering teams. For developers, this means onboarding onto complex codebases faster. For AI agents, it means getting the necessary code context to minimize hallucinations and maximize cohesion within the wider codebase. Sourcebot solves this by giving developers and AI agents the ability to regex search across millions of lines of code instantly, as well as ask questions across thousands of repos using any flagship reasoning model. Being open source and on-prem, we can get deployed in enterprises within minutes before other tools even get approval. We met a decade ago at McGill University and have been building together full time for over 2 years. We’ve personally felt the pain of understanding large codebases while working at Microsoft, EA, Ubisoft, Google, and Meta.

Rivet is a visual AI editor for product designers to make UI changes. Designers ship the changes they make directly to their codebase. The most painful problem for designers today is that their vision doesn't match code. Rivet replaces slow collaboration between designers and engineers by letting designers just do it themselves. Rivet's editor helps turn product designers into design engineers. Design-led companies in YC F25 are Rivet customers. Learn more at rivet.design

Our agents run hardware engineering tasks that normally take hours or days in just a few minutes, allowing engineers to process 100x more data and information. Our platform allows hardware engineers to orchestrate agents for tasks such as analyzing failures across entire test campaigns, pulling the right data and KPIs from their databases, checking how conditions (like temperature or load) affect performance and reliability, and then document findings in reports and dashboards.

We derive training data from the world's brightest minds, enabling LLMs to achieve state-of-the-art model performance.

Specific lets users build and deploy backends without code. They simply connect their preferred coding agent and we build, deploy and scale a backend for any project automatically.

Semble AI builds AI agents that design building-systems (fire, HVAC, plumbing, security). Construction companies use Semble to cut down weeks on commercial and residential projects. The $600B building-system integration industry still runs on spreadsheets and manual drawings, even as building codes rapidly evolve and become more localized. It’s a massive blind spot for the tech world. Jonathan and Ethan met studying computer science at Stanford. Jonathan worked at Convergint, one of the world's largest building system integrators, specifically for the purpose of learning how this industry works. Ethan is obsessed for a different reason: His house burned down in 2017 due to a faulty fire system. They are determined to make Semble the industry standard for construction design.

Stellon Labs is an AI research lab that is building tiny frontier AI models that can run on edge devices like smartphones, wearables and embedded systems. Our first open source model, KittenTTS, is a super-tiny text-to-speech model, that got 8K Github stars and 45K model downloads within 2 weeks of launching.

Panels is an audio data platform that delivers high-quality speech datasets from vetted, diverse contributors to power training and evaluation of foundational voice models.

Datafruit is the first agentic DevOps engineer. It understands your deployment standards, design docs, and DevOps practices, then reasons across them to reduce cloud waste, prevent deployment delays, and eliminate wasted time across the stack. Reach out to us: founders@datafruit.dev

Imagine a QA team of 5,000 testers available 24/7 on every new feature you ship. That's Ghostship. Our AI agents will crawl through your product and interact with it like users would to find the bugs (especially edge cases) that lead to churn—all at a fraction of the cost.

Fluidize accelerates R&D for scientists and engineers by using AI to build and run simulations and experiments. Our platform speeds up development pipelines by automating setup, execution, validation, and scaling, allowing engineers to focus on their science.

SigmanticAI is building an AI-native hardware development assistant that automates the entire RTL design flow, from natural language to synthesizable HDL and testbenches, inside a seamless VSCode fork. Powered by fine-tuned Verilog LLMs, reinforcement learning, and real compiler feedback, SigmanticAI iteratively refines code until it compiles and passes synthesis, no matter how complex the design. It’s like the Cursor for HDL design. In addition to code generation, SigmanticAI can generate token-level annotations and onboarding documents to accelerate ramp-up for new engineers. With support for both cloud and on-prem deployment, it integrates with existing EDA tools to dramatically reduce debug time, improve collaboration, and accelerate hardware design across teams

Embedder is a coding agent that can write, test, and debug firmware on both physical and simulated hardware. Supporting 20+ MCU/SoC platforms, it accelerates embedded systems development across semiconductors, automotive, medical devices, aerospace, IoT, and consumer electronics.

CUDA for phones & consumer hardware: Cactus is used by 3k+ developers and 100+ products to run AI locally on consumer hardware. It is open-source! Check out the repo: https://github.com/cactus-compute/cactus

Every successful tool is a bet on efficiency. A waterwheel grinds more grain per unit effort than a quern. A transistor switches more operations per watt than a vacuum tube. This is civilization's pattern: do more work with less energy. For ten thousand years, efficiency meant physical work. Intellectual work rode the surplus. Better farming, manufacturing, transport. But the brain itself bottlenecked every intellectual task. Compute changes this. For the first time, we can drive efficiency gains in intellectual work directly. Any repeatable job with measurable output has an efficiency ratio. Useful work divided by energy consumed. Intelligence per watt. Humans perform tasks at some quality-weighted outcomes per kilowatt-hour. AI systems do the same jobs. We can measure both the same way. AI is crossing the human baseline. Domain after domain. The world's hardest problems are information problems, and human intelligence is no longer the limit. The cost of intelligence per unit of energy is the limit. Every order of magnitude drop in cost expands the set of solvable problems. Our mission at Wafer is to maximize intelligence per watt by using AI to optimize AI infrastructure, achieving thousands of times better energy and cost efficiency. We want people to do their life's work here in pursuit of radical abundance. We believe cheap intelligence is the most essential piece of technology for a future of abundance. We will build the future with intelligence "too cheap to meter."

Keystone is an AI engineer that joins your team and understands your product from codebase to production. It can triage tickets, fix bugs, and automatically resolve incidents, autonomously.

Cyberdesk is the first self learning computer use agent for developers to automate desktop workflows. For example, one of our customers is building an AI agent for hospital patient intake, and they’re using us to automate an entire team of people manually clicking and typing into a desktop app to book appointments. We launched mid July, and our agent is already operating in production environments, creating appointments in electronic health record apps and processing files in legacy ERPs. We’ve built the first computer use agent that memorizes tasks and repeats them quickly while still adapting to unexpected changes on the screen. A good analogy is to how humans use computers: once we get used to an app, we use it much faster, while still adapting to random popups and crashes. This new paradigm for computer use will be needed by every company automating human workflows on computers. Mahmoud previously built robotic process automation solutions impacting 20K+ employees at a Fortune 100 company. He also built AI & ML solutions at Baylor College of Medicine Neuroscience & Texas Children's Hospital + co-published a paper at the Rice Networks Group. Alan is ex-NASA and previously dropped out to be the first founding engineer at a PearX startup. He is a second time founder, having previously built and scaled a consumer AI app to thousands of paying users. Computer-use agents will automate the $6T dollars spent on enterprise knowledge work and Cyberdesk will be the platform to power this. We’d love to talk with you! https://cal.com/mahmoud-al-madi-klrs5s/30min

What if every experiment you wanted to run could be modeled using AI? Godela is an AI-powered physics engine that gives engineers faster, cheaper replacement to simulations and physical prototypes. No set up, no wait. Just ask—and get simulation quality result.

StarSling is building an agentic developer homepage that automates all the tasks that eat up a developer’s time after they’ve left their code editor: deployments, performance, incidents, and bugs. Open your homepage, click on a GitHub, Linear, or Sentry issue and you’ll see an Autofix button that triggers an AI agent and opens up a Pull Request with a fix, all without leaving your homepage.

Mesmer is Cursor for CTOs. We give founders and CTOs full visibility into their org without drowning in meetings or chasing updates. We are a team of repeat founders and CTOs with 15+ years of experience each, including leading product development togehter at Origin Financial, a fintech started by Mesmer's CEO, as it scaled to 8-figure ARR, 100+ employees and a $400M valuation. Mesmer reached 6-figure ARR within a week of launching and is already live with companies worth over $8B, including Webflow and Origin Financial.

Docket lets you write end-to-end tests in plain English and keeps them up to date automatically—powered by real user sessions.

Attune makes blazingly fast build tools that require zero migration effort. As AI enables developers to write code faster than ever, slow builds are increasingly becoming the bottleneck in development velocity. Developers regularly lose hours of productivity every day waiting for their builds. Imagine being able to write code in 1 minute, but needing to wait 30 minutes to compile, deploy, and test it. Existing solutions either require painful migrations to new tools (e.g. Bazel) or rely on just using bigger servers to run your builds. Instead, we do native, first-class integrations into compilers and build systems. With Attune, you don't need to integrate a new tool. Just make a one-line change from `cargo build` to `hurry cargo build` for 20x faster builds. Eliza (ex-Google) and Xin worked together for 3 years at FOSSA, where Eliza was Head of Engineering and Xin was Head of Product. Eliza brings a decade of programming languages and build systems expertise, while Xin brings a decade of experience building developer tools products, most recently as VP of Product at Teleport (S15). Having experienced the pain of slow builds firsthand across hundreds of production codebases, we're building the solution we've always wanted.

Alkali is building the co-pilot for chemical process design. Spot design errors earlier, get the right equipment sooner, and build chemical projects faster.

We supercharge agents from Cursor to AgentKit with product and team-level context. Connect us once to where your internal data lives, then create secure data gateways with granular cross-platform permissions, comprehensive monitoring, and robust security filtering.

Building RL environments for the next generation of capabilities in frontier models

Human Behavior uses vision models to watch all user web sessions so you know exactly how users use every part of your product.

HUD (YC W25) is developing agentic evals and RL environments for Computer Use Agents (CUAs) that browse the web for frontier AI labs. Our CUA Evals framework is the first comprehensive evaluation tool for CUAs. People don't actually know if AI agents are working reliably. To make AI agents work in the real world, we need detailed evals for a huge range of tasks. We're backed by Y Combinator, and work closely with frontier AI labs to provide agent evaluation and training infrastructure at scale.

Truffle AI makes it easy for developers to integrate AI agents into any software application. We do this by exposing agents as simple APIs that can be called from anywhere. Developers have used Truffle to add customer support agents into WhatsApp and analytics agents into Slack.

Trim is building a general intelligence AI model that can simulate real-world physical systems evolving over time. For example, given the starting position of waves on a beach, the model generates how those waves move forward in time.

Twilio for AI agents. We help AI products talk and work to their users through email, Slack, SMS, WhatsApp and more.

Olive connects to your database & third party services to help you build admin dashboards and support tools in minutes.

Oki AI tells you everything you need to know to run your company. By reading your team’s code, tickets, messages, and more, Oki delivers personalized - and interactive - updates daily to you and other leaders.