Web Development Startups funded by Y Combinator (YC) 2026

Automate consent and user data rights compliance. Built for performance and full developer control.

We are making the world's fastest browser for your AI agents. Agents don’t need to see UIs like us humans do. We give agents a semantic understanding of the web instead of brittle visual interfaces. Your agents can perform deep research, large-scale scraping, and complex automation—more efficiently with our agentic browser that turns the web into a native protocol for LLMs.

A Coast (containerized host) is a local development runtime. Coasts let you run multiple isolated environments for the same project on one machine. As AI coding agents increasingly work in parallel across git worktrees, developers hit painful conflicts — clashing ports, duplicated databases, and fragile per-branch setup. Coasts solve this by giving each worktree its own fully isolated runtime, so multiple agents can build and test side by side without stepping on each other.

Floot lets non-coders & entrepreneurs build real web apps that actually work. We’re taking a new approach by building everything from the ground up for AI. ✨ Try building an app at floot.com Existing AI app builders fall short of enabling non-coders to build real, serious apps. They often: - Break down when building anything more than a prototype or toy app - Have non-coders stuck with errors they don’t understand - Require non-coders to handle multiple services designed for developers (e.g. for backend, database, hosting, etc) The fundamental problem: these AI app builders just cobble together existing developer tools and slap AI on top, but these tools were designed for humans and not for AI. The result? Non-coders get excited, start building, hit a wall, and then abandon their projects. Floot is purpose-built for AI. Our secret sauce: 1) Instead of reusing a coding framework designed for humans, we created a specialized framework that dictates how AI should write code and how the code runs on our infrastructure. This allows us to enforce best practices, detect errors earlier, and give the best feedback to the AI. As a result, Floot can write better code and fix issues more effectively. 2) Floot has the entire tech stack built-in (backend, database, hosting, etc) so building and managing an app feels seamless, especially for non-coders. And because we control every layer of the stack, we can optimize each layer for AI-first coding. Because of this, non-coders can get more done with less time and prompting. They can finally build serious apps that work, instead of getting stuck in frustrating error loops and then abandoning their projects. We also built a highly scalable hosting system directly on AWS so Floot apps can handle real traffic and business demands. This means non-coders can build, deploy, and scale their apps on a single platform seamlessly. Plus, Floot is really fun to use! Try building an app at floot.com

stagewise builds an open-source frontend coding agent for real codebases. We enable backend devs, designers and product managers to build pretty and functional web apps in a simple and visually guided manner - no matter the used tech stack. stagewise lives right inside your browser, makes changes in your local codebase and is compatible with all kinds of frameworks and setups - allowing it to be retrofitted into any existing project. Our agent enables you to show and tell what you want to change - all while using your app on localhost and without having to switch to external tools. Making changes is as easy as selecting elements, giving a simple prompt like “make it green and put it in the top right corner”, and immediately seeing the result. We're two founders from Germany who met while working at a B2B SaaS startup. With Glenn's background in building dev tools for enterpries (Rheinmetall, Miele), as well as Julians experience in building web apps used by thousands (saasmetrix, strukto.io), we have the unique blend of experience and product sense needed to build this. After making our initial launch with the open-sourced toolbar that puts your favorite coding agent right inside your browser and going viral with it, we’re now launching a high-speed coding agent dedicated to frontend development - taking our product and the experience of our users to the next level. Our vision is to replace frontend devs completely, by gradually enabling both the backend devs, but also less technical designers and product managers to create well-designed applications. We start with developers who lack design experience, but our ultimate goal is to change how products are built.

Wavedash uses cutting edge browser technology to let gamers play the latest releases with no downloads or installation.

assistant-ui helps frontend developers add AI chat to their apps. Our product is used by several dozen companies, like LangChain, Stack AI, Browser Use, and Athena Intelligence. We're building an open source Typescript/React library and a backend as a service, with first class integrations into popular agent frameworks like LangGraph and Vercel AI SDK.

Vibe enables everyone to turn their thoughts into real world apps through conversation. Let’s vibe code the future.

Ben and Jacob met in Calculus class in 10th grade, and tried founding a startup in high school — it didn’t go anywhere. During high school, Ben lead the frontend team for the World Health Organization’s COVID-19 App Team. After high school, Jacob went to Apple and Ben went to college. When there was an opening on his team, Jacob had Ben apply, and Ben left UChicago to go work at Apple. They spent about 2 years at Apple as Senior Engineers in the Conversational Engineering Department, before leaving to found Freestyle. Freestyle is directly inspired by what they saw as their failures of the tech they worked with at Apple.

Pazi enables people to build agents that run all operations in a company. You create an agent for a position (eg. developer, devops, social media manager, SDR, etc.), you give it a goal (eg. reach 10k followers on X) and let it create a plan, start checking in with you, oversee how the goal is coming up.

Repaint lets you build professional websites by chatting with AI. It interviews you, researches you online, and generates a custom websites. Then you can edit anything by asking the AI. Our vision is to merge traditional website builders with AI coding tools, creating a new way for anyone to make more advanced software.

refine is an open-source, headless React framework for rapidly building enterprise web applications. It eliminates many repetitive tasks like ➡️ CRUD operations ➡️ State management ➡️ Routing ➡️ Authentication ➡️ Access Control ➡️ i18n and saves days of development time. So far, thousands of great projects have been built by 15,000+ monthly active refine developers. Use cases are ranging from admin panels, dashboards, and internal tools to B2B solutions and complex SaaS interfaces. refine is backed by a strong community featuring 16K GitHub stars ⭐️, 180+ contributors and 2,500 Discord members. Thanks to it's unique "Headless UI" approach, refine works with any custom design. It has also ready-made integrations with 4 most popular UI frameworks: Ant Design, Material UI, Chakra UI and Mantine. refine is totally backend agnostic and it can connect to 15+ backend services out-of-the-box, incl. custom REST & GraphQL API's. With refine, developers always have 100% control over their projects as they build, style and deploy the way they like.

Reflex is the operating system for building mission-critical enterprise applications. Today’s enterprise stack is fragmented. Shipping an app requires stitching together multiple tools and coordinating across multiple roles. Reflex replaces that complexity with a single, unified platform to build, deploy, and manage production applications end-to-end. We empower teams to own the entire lifecycle of their apps — from idea to production — without needing specialized infrastructure, DevOps, or platform teams. We do this by providing solid, reusable abstractions at both the framework and infrastructure layers. Because we own the underlying open-source framework and the platform it runs on, we can manage the full lifecycle of the application seamlessly. With Reflex, teams securely connect to company data, use AI to build standardized applications on top of our open-source framework, and deploy with a single click to share across their organization. We’re replacing the fragmented enterprise stack — and the organizational bottlenecks that come with it. Founded by Alek Petuskey and Nikhil Rao, Reflex has powered over 1 million applications, earned 28,000+ GitHub stars, and is used by 30% of Fortune 500 companies for internal tools and data-driven applications.

CodeCanary is an AI product engineer that proactively finds and fixes bugs, improves conversion rate, and gathers insights about your product. CodeCanary runs regularly and connects directly to Slack, GitHub, and PostHog.

We build devtools. Orca is an open-source Cursor—a local-first AI coding environment. Stably is our AI testing platform that writes, runs, and maintains E2E tests in CI. Developers use Orca and Stably to ship faster with more control—coding with their own AI setup and merging with confidence in minutes.

Awesomic matches companies with top & vetted product talents in 24 hours. Find your designers, engineers or no-coders in a few clicks. They deliver you results through our app, every 24 business hours guaranteed, for a flat monthly subscription. Successfully matched 4000+ companies, including 400+ YC startups, with their talents who completed over 14 000 projects in the app. Book a live demo here: https://www.awesomic.com/demo Portfolio – https://www.awesomic.com/portfolio Cases – https://www.awesomic.com/case-study

Whalesync makes data syncing easy. Our automation platform syncs data between key business tools like Webflow/Wix/WordPress and Airtable/Notion/Google Sheets. We give marketing teams two-way, real-time sync, so they can manage their website from their favorite collaboration tools. Whalesync launched during Y Combinator’s S21 cohort. Since then we’ve raised from some of the world’s top investors. We’re now trusted by hundreds of companies like [Ramp](https://ramp.com/), [Webflow](https://webflow.com/), and [Alchemy](https://www.alchemy.com/), and process millions of transactions every day. Many of our customers enjoy the product so much they [tell all their friends](https://whalesync.com/customers).

WeWeb is a visual programming tool that allows you to build user interfaces on top of existing databases & auth systems. It allies the short learning curve of no-code with the freedom of code. CONTROL & FREEDOM – Build pixel-perfect frontends with drag-and-drop UI elements and no-code CSS properties but have the option to add custom code or import your own Vue.js components. CODE BEST PRACTICES – Follow development best practices by building components, global workflows and re-usable functions with no-code triggers and formulas with the option to add custom JS where needed. NO VENDOR LOCK-IN – WeWeb generates a standard PWA-ready Single Page Application and allows you to deploy your projects on your own infrastructure. Build in no-code, host on-premise.

The Sails Company was founded by the original author and maintainers of the Sails framework. In addition to free and open-source software, The Sails Company offers a full-service web & mobile studio and professional support for the tools we maintain.

React components to build charts and dashboards

What if you could build web apps as easily as you make a Figma design or edit a Google Doc? Enter Mocha. We've reimagined app development with a state-of-the-art coding agent that builds for our users. Want to launch that app idea? Need to build something for your community? Looking to prototype faster? Start here. We've removed the barriers between idea and execution. Our mission is to empower everyone to build for the web, our vision is personal software.

At Aptible, we envision a world where developers achieve more with less infrastructure. We’re building the platform that empowers developers at companies of all stages of development to move beyond the traditional method of managing infrastructure—DIY with expert infrastructure and platform engineers on AWS, GCP, or Azure. We’ve done this through our secure, compliant, reliable, and scalable Platform as a Service that’s been used by thousand of developers, hundreds of companies, and dozens of publicly traded and unicorn companies since 2013.