How to Use Gemini 3 for Rapid Web Design Prototyping

Figma-to-code workflows are starting to feel outdated. As of November 2025, Gemini 3 Pro, Google’s latest frontier model, can generate full web page prototypes directly from a text prompt, complete with React code and a live preview inside Google AI Studio’s Build mode. Instead of painstakingly drawing frames, exporting assets, and handing them to developers, you can “vibe code” high‑fidelity layouts in minutes and refine them conversationally.

This evergreen guide explains how to use Gemini 3 for rapid web design prototyping. You’ll learn how Build mode works, how to write prompts that produce quality UI, how to iterate visually without touching CSS, and how Gemini fits alongside Figma rather than simply replacing it. If you’re a web designer or product designer looking for a faster, AI‑powered design process, this walkthrough is for you.

What Gemini 3 can do for web design prototyping

Gemini 3 Pro, released November 18, 2025, is Google’s most capable multimodal and coding model to date. According to Google DeepMind’s official model page and launch blog, Gemini 3 Pro specializes in “vibe coding” high‑quality front‑end experiences and outperforms Gemini 2.5 Pro by over 50% on coding benchmarks. In practice, this means it can:

• Generate complete React web apps from a natural language prompt using Google AI Studio’s Build mode.
• Render an instant live preview panel so you can see and interact with the generated UI.
• Adjust layout, typography, and interactions through follow‑up prompts or annotation mode (click-and-describe edits).
• Export production-ready code you can continue building with React 19.2 or frameworks like Next.js 16.

In Google AI Studio’s Build mode, when you “run” a prompt, Gemini 3 Pro creates a React-based web app scaffold (with files like geminiService.ts) and shows a live preview on the right. Designers can then iterate on the design and copy or download the code as a starting point for production.

This makes Gemini 3 ideal for rapid web design prototyping: you can move from idea to live, clickable layout in minutes, then polish in code or hand off to engineering.

Setting up Gemini 3 in Google AI Studio

To use Gemini 3 for rapid web design prototyping, you’ll work primarily in Google AI Studio’s Build mode.

1. Create or sign into your Google account. Go to Google AI Studio.
2. Switch to Build mode. In AI Studio, open the Build tab (this launches the apps interface at /apps).
3. Select Gemini 3 Pro. When prompted to choose a model, pick gemini-3-pro-preview (or the latest Gemini 3 Pro variant listed in the UI). This is the model tuned for advanced reasoning and front‑end “vibe coding.”
4. Confirm web app type. By default, Build mode generates a React web app. In the Settings menu you can keep React, or switch to Angular if your team prefers it.

Once configured, you’ll see:

• An input box (“Start with a prompt”) at the bottom.
• Optional AI chips to add capabilities like image generation or Maps.
• A central file tree / code area.
• A right‑hand live preview pane with Preview and Code tabs.

From prompt to live prototype: step-by-step workflow

This is the core Gemini 3 rapid prototyping loop: describe → generate → inspect → refine → export.

1. Write a design-aware prompt

Your first prompt is effectively the creative brief and UX spec. Gemini 3 Pro can handle quite detailed instructions. Include:

• Page purpose and audience (e.g., SaaS marketing, portfolio, dashboard).
• Visual style (minimal, brutalist, neumorphic, material, etc.).
• Layout structure (hero, features grid, testimonials, pricing).
• Brand cues (colors, tone of voice, type style).
• Technical preferences (React 19, CSS modules, Tailwind, Material Web components).

// Example first prompt for Gemini 3 in Build mode
Design and implement a responsive single-page marketing site
for a B2B analytics SaaS called "Lumetric".

Requirements:
- Built with React 19 and modern, semantic HTML.
- Use a clean, modern visual style inspired by Material Design 3.
- Sections: 
  1) Sticky nav with logo and primary CTA
  2) Hero with headline, subcopy, product screenshot placeholder
  3) 3-column feature grid with icons
  4) Social proof strip with 4 logo placeholders
  5) Pricing table with 3 tiers
  6) Footer with links.

Design details:
- Primary color: #4F46E5, accent: #F97316, neutral background.
- Rounded corners, subtle shadows, large, readable typography.
- Smooth scroll for nav links.
- Use a single page layout with internal anchor links.

Please generate production-quality React code and CSS, 
and ensure the layout looks polished at desktop and mobile breakpoints.

Paste this into the Build mode input, then click Run. Within seconds, the right panel shows a live preview of your new web design prototype.

2. Inspect the live preview and code

AI Studio’s live preview is central to rapid prototyping:

• Use the preview to scroll, hover, and click through the site as if it were deployed.
• Toggle between desktop and mobile-sized windows to gauge responsive behavior.
• Switch to the Code tab in the preview panel to see the generated React components and styles for the current view.

In the file tree you’ll typically see an App.tsx or similar entry file, component folders, and a geminiService.ts file that encapsulates Gemini API calls if your app uses them. For static marketing pages, geminiService.ts may be minimal or unused at first.

3. Iterate with natural language and annotation mode

Instead of rewriting CSS or JSX by hand, you can ask Gemini 3 to adjust the design.

• Chat-based edits: In the Build mode chat, reference specific sections:
  “Tighten the hero section spacing, make the headline slightly larger, and change the CTA button to solid orange with white text.”
• Annotation mode: Turn on Annotation mode, click a component in the preview (e.g., a pricing card), and type instructions such as “Increase card border radius, add a subtle shadow, and highlight the middle plan more strongly.” AI Studio captures a screenshot and sends a structured prompt to Gemini 3, which then updates the code.
• Structural changes: You can ask: “Add a testimonials carousel below the pricing section” or “Replace the feature grid with a 2-column layout: text on the left, illustration on the right.”

Gemini 3 is particularly strong at these iterative changes, aligning with Google’s description of the model as excellent at small, compound improvements over time.

4. Export your prototype to React or Next.js

Once the design prototype feels solid:

• Download as ZIP: Use the export option to download the generated React project.
• Push to GitHub: Connect GitHub and push the app to a repository to integrate into your team’s CI/CD and design system.
• Adapt to Next.js 16: If your stack uses Next.js, open the project locally, then migrate key components into app/ or pages/ routes following the Next.js 16 docs.

// Example: integrating Gemini-generated hero into a Next.js 16 app
// app/page.tsx

import Hero from './components/Hero'; // copied from AI Studio export
import Features from './components/Features';
import Pricing from './components/Pricing';

export default function HomePage() {
  return (
    <main className="min-h-screen bg-slate-950 text-slate-50">
      <Hero />
      <Features />
      <Pricing />
    </main>
  );
}

From here, engineering can wire up real data, integrate authentication, or connect to CMS content while preserving Gemini’s design.

Prompt patterns for high-quality AI web design

Using Gemini 3 for AI web design is less about “magic” and more about giving the model a solid brief. These patterns tend to produce stronger results:

• Describe content hierarchy, not pixels. Focus on what the user needs to see first, second, third, and what actions matter.
• Reference known systems. Ask for “Material Design 3-influenced cards” or “a layout similar to modern SaaS landing pages like Notion or Linear,” while keeping it generic to avoid copying.
• Specify responsiveness. Include instructions like “grid collapses to a single column under 768px,” or “hero image stacks under copy on mobile.”
• Ask for accessibility. e.g., “Provide sufficient color contrast, proper heading hierarchy, and visible focus states.”
• Iterate in layers. Start with a wireframe-level layout, then in a second pass, ask Gemini 3 to “upgrade the visual design to a high-fidelity marketing site with carefully tuned typography and spacing.”

“Like a skilled UI designer, [Gemini 3 Pro] can range from well-organized wireframes to stunning high-fidelity prototypes.”

Michele Catasta, President & Head of AI at Replit, via Google DeepMind’s Gemini 3 page

This ability to move from low‑fidelity structure to high‑fidelity UI within the same tool is what makes Gemini 3 such a strong web design prototyping companion.

Gemini 3 vs Figma: replacement or companion?

Gemini 3 isn’t a wholesale Figma replacement; it solves a different part of the workflow. As of late 2025, Figma has evolved into a full “design OS” with tools like Figma Draw, Sites, Buzz, and Make, and even integrates Gemini 3 Pro inside Figma Make for code-backed prototypes. Still, teams face friction when moving from static Figma frames to real code.

A productive 2025 workflow often looks like:

• Use Gemini 3 to quickly explore several coded layout concepts and interaction patterns.
• Pick the strongest direction and port UI decisions (spacing, hierarchy, typography) into Figma for systematization and cross-platform alignment.
• Refine micro-interactions and brand details in Figma, then either export to code via Figma’s tools or update the Gemini-generated codebase manually.

Best practices and limitations for AI-powered web prototyping

To get the most from Gemini 3 for web design prototyping, keep these practical guidelines in mind.

Code quality and maintainability

• Review structure: Ensure components are factored logically (e.g., <Hero/>, <Features/>, <Pricing/>) rather than a single monolithic file.
• Align with your stack: If your team uses Tailwind, request it explicitly in the initial prompt. The same applies to CSS-in-JS, Material Web components, or design tokens.
• Refine state handling: For interactive prototypes (forms, modals, carousels), review how Gemini 3 manages state (hooks, context) and refactor as needed.

API key and deployment safety

Build mode uses placeholder environment variables like process.env.GEMINI_API_KEY in generated code. Google’s documentation warns you should never ship a client-side app with a real key embedded. Instead:

• Move Gemini API calls to a secure backend (Node, serverless function, or Next.js API route).
• Use AI Studio’s Cloud Run deployment for experiments, but lock down keys and scopes for production.
• For design-only prototypes, consider stubbing API calls until engineering takes over.

Where Gemini 3 shines vs where humans still lead

• Shines at: Quickly generating multiple layout options, establishing responsive patterns, roughing out visual systems, and converting product copy into structured sections.
• Still needs designers for: Brand nuance, motion language, interaction details, accessibility audits, UX research synthesis, and aligning with multi-product design systems.

Example: turning a text brief into a live dashboard prototype

Here’s a compact example you can adapt for your own rapid prototyping session.

// Prompt for a Gemini 3-powered dashboard prototype

Design and implement a responsive analytics dashboard web app
for a product manager.

Use:
- React 19 with functional components and hooks
- Modern CSS (utility-style or CSS modules)
- Accessible, keyboard-navigable UI

Layout:
- Left sidebar with logo, nav items, user avatar
- Top bar with date range picker and search
- Main content: 
  - KPI cards row (4 cards)
  - Line chart area
  - Table of recent events

Design:
- Dark theme with indigo accents
- High contrast text
- Smooth hover states and focus outlines

Include realistic placeholder data and simple client-side filtering.

Run this in Build mode with Gemini 3 Pro selected. Within a minute you’ll have:

• A working dashboard layout with basic interactivity.
• React components you can tailor to your real metrics APIs.
• A strong starting point to refine visually, either in-code or by mirroring the layout in Figma.

Conclusion: redesign your design process with Gemini 3

Gemini 3 changes web design prototyping from a manual, pixel-first exercise into a fast, code-native workflow. In Google AI Studio’s Build mode, you can describe a page, see a live React prototype in seconds, and then iterate conversationally instead of redlining mockups. Used alongside Figma’s mature design system capabilities, Gemini 3 becomes a powerful accelerator for both designers and developers.

For your next project, start with a Gemini 3 prototype rather than a static wireframe: capture your UX intent in a prompt, generate two or three layout options, and refine the strongest one with annotation mode. Then export the code, wire it up to your stack, and polish the visuals in Figma where needed. As AI web design tools continue to mature through 2025, the teams that learn to collaborate with models like Gemini 3 will ship better, more consistent experiences in a fraction of the time.