The best open source alternative to Quant-UX is Penpot. If that doesn't suit you, we've compiled a ranked list of other open source Quant-UX alternatives to help you find a suitable replacement. Other interesting open source alternative to Quant-UX is Grida.
Quant-UX alternatives are mainly UI/UX Design Tools but may also be Online Design Tools or Low-Code/No-Code Platforms. Browse these if you want a narrower list of alternatives or looking for a specific functionality of Quant-UX.
Design, prototype, and hand off to developers in one platform. Supports design systems, tokens, flexible layouts, and AI workflows with real CSS/HTML output.

Penpot is a browser-based design and prototyping platform built for teams working on digital products. It covers the full design process, from early wireframes through polished UI, interactive prototypes, and developer handoff, without requiring separate tools for each stage. It's self-hostable, so teams with strict data requirements can run it on their own infrastructure.
The core workflow connects designers and developers more directly than most tools. Instead of exporting assets and writing specs separately, Penpot generates 1:1 CSS, HTML, SVG, and JSON directly from the design. What you see in the canvas is what developers get in code, which cuts down on the back-and-forth that usually happens during implementation.
Key capabilities include:
Penpot is a practical alternative to Sketch or Adobe XD for teams that want full control over their tooling. Because it's open source and web-native, there's no per-seat licensing tied to a vendor's pricing decisions, and it works across operating systems without a desktop install.
It suits product teams where designers and engineers work closely together, particularly those building design systems at scale or looking to bring AI tooling into their existing design process.
Looking for open source alternatives to other popular services? Check out other posts in the alternatives series and openalternative.co, a directory of open source software with filters for tags and alternatives for easy browsing and discovery.
Design and build web applications on an open canvas with AI-powered tools, Figma integration, pixel drawing, and a modular SDK built for extensibility.

Grida is an open source canvas editor aimed at designers and developers who want a single tool for visual design and web app building. It covers the range from polished UI/UX layouts to pixel art, with enough extensibility that developers can embed it, script it, or build entirely new tools on top of it.
The canvas itself is general-purpose. You can work from templates, drag in widgets and icons, write copy with an AI assistant, and edit text directly on the canvas. Figma import and export means you're not starting from scratch if your team already has assets in Figma. For pixel work, there's a dedicated free pixel drawing mode built into the same editor.
What separates Grida from tools like Penpot or Excalidraw is its developer-first architecture:
For teams, Grida offers enterprise options with on-premise deployment and custom solutions, so it's not just a solo design tool.
It fits developers who want a visual web builder they can actually hack on, and designers who need something between a lightweight whiteboard and a full-featured UI tool.