Builder.io
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Last reviewed
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Builder.io is a San Francisco visual development platform that pairs a headless, visual content management system with a suite of AI design-to-code tools. Founded by Steve Sewell and Brent Locks, two former engineers from the fashion commerce company ShopStyle, the company built its early business around a drag-and-drop editor that lets marketing, product, and design teams build and edit pages visually while emitting production code that plugs into an existing codebase. Since 2023 it has reoriented around AI: its Visual Copilot plugin converts Figma designs into framework code, and its Fusion agent, launched in late 2025, generates and edits production web applications. Builder.io is also a prolific open-source contributor, sponsoring the Qwik web framework (created by Angular author Misko Hevery, who serves as the company's CTO) and maintaining the Mitosis cross-framework compiler and the Partytown script-offloading library.
Builder.io (the company behind builder.io) should not be confused with Builder.ai, an unrelated London app-development startup that filed for bankruptcy in 2025. The two are separate companies with different founders and products.
The platform's central idea is to decouple the visual authoring of web content from the code that renders it. A non-technical user assembles a page in a visual editor using either generic blocks or custom components that developers have registered from the application's own codebase. The resulting layout is stored as structured JSON in Builder's headless CMS and pulled into the live site through an SDK, so the same content can be served to a React, Vue, Angular, Svelte, or other front end without the marketer ever touching code. This positions Builder.io between traditional page builders, which tend to lock teams into proprietary output, and pure headless CMSes, which usually offer no visual editing at all.
On top of that CMS foundation, the company has layered a set of AI products aimed at the boundary between design and engineering. The throughline across the catalogue is generating usable front-end code from higher-level inputs: a Figma file in the case of Visual Copilot, or a prompt, ticket, or product requirement document in the case of Fusion.
Steve Sewell and Brent Locks met while working together at ShopStyle, where Sewell led web engineering and oversaw the rebuilding of the company's consumer brands. They repeatedly hit the same bottleneck: marketing, sales, and merchandising teams needed frequent landing pages and homepage changes, and those requests clogged the engineering backlog. Existing no-code tools either could not integrate with the company's stack or still depended heavily on developers. The pair built an internal visual editor that produced clean, production code rather than the bloated markup typical of legacy site builders, and spun it out as Builder.io. The company is headquartered in San Francisco. It was incorporated in 2018, and Builder's own announcements and press coverage generally date the company's founding to 2019, the year it launched its commerce-focused product.
The early product targeted e-commerce brands running headless architectures, offering native Shopify integration plus connectors for other commerce platforms, A/B testing, and conversion measurement, all editable without engineering involvement. Early customers cited by the company included Everlane, Vistaprint, Atoms, and ShopStyle itself.
Builder.io has raised roughly $37.25 million in disclosed equity across three announced rounds. Greylock Partners led the first two; Microsoft's corporate venture arm led the third.
| Round | Date announced | Amount | Lead investor | Notable participants |
|---|---|---|---|---|
| Seed | October 1, 2020 | $3.25M | Greylock Partners | Founders and executives from Allbirds, Caviar, Harry's, PopSugar, and Warby Parker |
| Series A | October 18, 2021 | $14M | Greylock Partners | Imaginary Ventures; angels including Michael Preysman (Everlane), Adam Blitzer (Datadog), Anthony Kennada |
| Venture round (M12) | April 24, 2024 | $20M | M12 (Microsoft's Venture Fund) | (Not disclosed) |
The seed round, announced in October 2020, was a $3.25 million raise led by Greylock with participation from founders and senior executives at consumer brands including Allbirds, Harry's, and Warby Parker. The $14 million Series A followed in October 2021, again led by Greylock and joined by Imaginary Ventures along with a roster of operator-angels such as Everlane founder Michael Preysman and Datadog COO Adam Blitzer. At the time of the Series A the company reported more than 400 customers, roughly six times its base at the start of that year, naming Everlane, Alo Yoga, Afterpay, and Vistaprint among them.
In April 2024 Builder.io announced a $20 million investment led by M12, Microsoft's venture fund. The company framed the capital as a way to grow its team and meet what it called extensive organic demand, and tied the raise to its newer AI products rather than to the original CMS. Builder.io has not publicly disclosed a valuation for any of its rounds.
A pivotal hire was Misko Hevery, the creator of Google's Angular and AngularJS frameworks and a co-creator of the Karma test runner. Hevery joined Builder.io as chief technology officer, a move announced around the company's 2021 Series A. He had begun experimenting with a new framework concept, which became Qwik, in January 2021, exploring how far the execution of client-side JavaScript could be delayed. After he joined Builder.io, Qwik became a full-time effort: by mid-2022 a dedicated team including Adam Bradley and Manu Martinez-Almeida was working on it within the company. Hevery's presence anchored Builder's open-source strategy and its later design-to-code work, since the same compiler technology that powers Qwik tooling underpins Visual Copilot.
The original and still-core product is a visual, headless CMS. Developers register components from their codebase, and content editors then drag those components onto a canvas to compose pages, marketing campaigns, and other content. Because the output is structured data delivered through an SDK rather than a fixed HTML bundle, the same content can render across different frameworks and channels. The CMS supports A/B testing, personalization, and analytics, and integrates with commerce platforms such as Shopify. Builder later packaged page-generation and optimization capabilities under a product it calls Publish.
Visual Copilot, launched on October 12, 2023, is Builder.io's Figma-to-code tool, distributed primarily as a Figma plugin. With a single click it converts a selected frame or layer into responsive front-end code. According to the company, the tool runs a three-stage pipeline rather than a single model: an initial AI model converts the flat visual structure of a design into a hierarchical code tree, the open-source Mitosis compiler turns that hierarchy into framework-agnostic component code, and a final fine-tuned large language model pass adapts the output to the user's chosen framework and styling library. Builder describes the underlying model as an in-house, fine-tuned system trained on more than two million data points; it has not publicly named a base foundation model.
Visual Copilot can emit code for React, Vue, Svelte, Angular, Qwik, Solid, React Native, and plain HTML, and supports styling options including plain CSS, Tailwind, Emotion, Styled Components, and Styled JSX. A notable feature is component mapping, where the tool uses AI to match reusable components in a Figma file to existing components in the user's repository, so the generated code reuses the team's design system instead of producing one-off markup. Builder has also shipped a Visual Copilot command-line interface and documented workflows that hand the generated code off to AI coding assistants such as Cursor and Windsurf for further iteration.
Fusion is Builder.io's AI agent for building and editing web applications, the product the company increasingly leads with. Builder announced Fusion 1.0 on November 14, 2025, billing it as an AI agent that connects product, design, and code in a single workflow rather than accelerating one role in isolation. Fusion integrates with Slack, Jira, Figma, and GitHub, so a Slack conversation can be turned into a feature request by tagging the Builder bot, or a Jira ticket can be assigned to the agent to spin up a branch and begin implementation. A visual canvas lets designers generate production code that uses a project's existing components and design tokens, and the agent can open and update pull requests in response to developer feedback.
The company describes a context engine that understands a team's APIs, data sources, and design systems to produce production-ready code, and that learns each team's patterns over time. Fusion supports React and other component-driven JavaScript frameworks, offers a choice of underlying models from OpenAI, Anthropic, and Google, and connects to external services through Model Context Protocol servers for tools such as Supabase, Netlify, and Zapier, with role-based access controls for larger teams. Builder.io states that, by the time of the 1.0 launch, Fusion had turned more than 10 million designs and product requirement documents into production features.
Builder.io maintains an active open-source portfolio, and its commercial AI tooling is built partly on these projects.
| Project | What it does | License | Approx. GitHub stars |
|---|---|---|---|
| Qwik | Resumable web framework for instant-loading sites | MIT | ~22,000 |
| Mitosis | Compiler that turns one component into React, Vue, Angular, Svelte, Solid, Qwik, and more | MIT | ~13,800 |
| Partytown | Moves third-party scripts off the main thread into a web worker | MIT | (open source) |
Qwik is a JavaScript framework for building instant-loading web applications. Its defining technical idea is resumability: instead of re-running application setup on the client to make server-rendered HTML interactive (the hydration approach most frameworks use), Qwik serializes the application state into the HTML so the client can resume where the server left off and download JavaScript only as specific interactions require it. Created by Misko Hevery, Qwik is developed under the QwikDev organization with Builder.io as a primary sponsor, is MIT-licensed, and carries roughly 22,000 stars on GitHub.
Mitosis is a compiler built around the slogan write components once, run everywhere. A developer authors a component in a JSX-like syntax, and Mitosis compiles it into idiomatic code for React, Vue, Angular, Svelte, Solid, Alpine, Qwik, and other targets, which lets a team ship a single design system across multiple frameworks. Mitosis is maintained by Builder.io, is MIT-licensed, and is the open-source compiler at the heart of the Visual Copilot pipeline, which is how a Figma design can be exported into so many different frameworks.
Partytown is a lazy-loaded library that relocates resource-intensive third-party scripts, such as analytics and tag managers, into a web worker so the main thread stays dedicated to the site's own code. Scripts are opted in by tagging them with a type="text/partytown" attribute. Builder originally published Partytown and later moved it under the QwikDev organization alongside Qwik. The company has said that combining Partytown and Qwik let it cut the JavaScript on its own website dramatically and reach a top Lighthouse performance score.
Builder.io grew quickly among e-commerce and consumer brands during its CMS era, reporting more than 400 customers by late 2021 and naming users such as Everlane, Alo Yoga, Afterpay, and Vistaprint. Independent revenue trackers have reported the company in the high single-digit millions of dollars of annual recurring revenue with a team in the low-to-mid 60s by 2023, though Builder.io has not officially confirmed those figures, so they should be treated as estimates.
The company's open-source work, particularly Qwik and the resumability concept, drew considerable attention in the web-development community and gave Builder.io outsized visibility for its size. The arrival of Misko Hevery, a well-known figure from the Angular ecosystem, reinforced that profile. The Microsoft-affiliated M12 investment in 2024 and a 2025 listing on the Google Cloud Marketplace signaled the platform's pivot toward AI-assisted application development and toward enterprise distribution. Builder.io's design-to-code positioning places it alongside a broader wave of AI code generation and AI-assisted vibe coding tools, though its particular niche, converting designs and product specs into code that reuses an existing component library, distinguishes it from general-purpose coding assistants.