How to Build a SaaS Using Google Stitch and Antigravity (2026 Guide)

The Fastest Way to Build a SaaS in 2026 — Design to Code Without Switching Tools

Six months ago building a SaaS meant weeks of setup before you wrote a single line of product code. You designed in Figma, handed it to a developer, waited for implementation, debugged the gap between what was designed and what got built.

Google Stitch and Antigravity together eliminate most of that pipeline. Stitch generates your full UI from a text prompt. The Stitch MCP server connects directly to Antigravity. Antigravity's agents read your designs and build the working application autonomously.

This guide walks through the complete workflow: from your first Stitch prompt to a deployed SaaS with real features, real auth, and real code — using two free Google tools that most developers have not combined yet.

🎯 Quick Answer (30-Second Read)

• Google Stitch: Free AI design tool from Google Labs — generates high-fidelity UI from text prompts, exports HTML/CSS and React code
• Google Antigravity: Free agentic IDE — autonomous agents plan, write, test, and debug code across your editor, terminal, and browser
• The connection: Stitch MCP server connects both tools — Antigravity agents read your Stitch designs and implement them directly
• What you build: A fully functional SaaS with designed UI, working frontend, auth, and backend — without a separate design handoff step
• Cost: Both tools are free in 2026 — Stitch at 350 generations/month, Antigravity free in public preview
• Best for: Solo founders, developers who hate designing, and small teams moving from idea to MVP fast

How Stitch and Antigravity Work Together

The key insight is the MCP connection in the middle. Without it, you export code from Stitch and paste it into your IDE manually. With the Stitch MCP server connected to Antigravity, agents have live access to your design context — they can query your screens, read your design system, and implement components that actually match what you designed.

Step-by-Step: Build a SaaS with Stitch and Antigravity

Step 1 — Design Your SaaS UI in Google Stitch

Go to stitch.withgoogle.com and sign in with your Google account. Select Web app and write a detailed prompt:
Design a SaaS dashboard for a project management tool.
Include: login screen, main dashboard with project overview cards,
sidebar navigation, task list view with status filters,
and a settings page. Dark theme, indigo accent color,
clean modern style. Show user avatar and notifications in header.

Stitch generates up to five interconnected screens simultaneously with a consistent design system — typography, colors, component library — applied across all screens.

Iterate on the canvas:

• Click any element to edit text or swap components
• Use voice commands to describe changes in real time
• Generate variants of individual screens by prompting specific changes
• Click Play to preview the interactive prototype flow

Export your DESIGN.md from the export panel. This agent-friendly markdown file captures your entire design system — colors, typography, spacing, component patterns. Antigravity agents will read this to stay consistent when writing code.

Step 2 — Set Up the Stitch MCP Server in Antigravity

Download Antigravity from antigravity.google/download and install it.

Open Antigravity and go to Settings → MCP Servers → Add Server:

{
  "name": "stitch",
  "type": "url",
  "url": "https://mcp.stitch.withgoogle.com/sse",
  "apiKey": "your-stitch-api-key"
}

Get your Stitch API key from your Stitch dashboard under Settings → API. Once connected, Antigravity agents can query your Stitch projects, read screen designs, and access your design system directly without manual copy-paste.

Verify the connection by opening Agent Manager and running:

List all screens in my Stitch project

The agent should return your screen names from Stitch. If it does, the MCP bridge is working.

Step 3 — Set Up Your Project in Antigravity

Create a new workspace for your SaaS:

mkdir my-saas && cd my-saas
npm create next-app@latest . --typescript --tailwind --app --src-dir
npm install @supabase/ssr @supabase/supabase-js stripe @stripe/stripe-js zod

Open the folder in Antigravity. Paste your exported DESIGN.md from Stitch into the project root — this gives every agent persistent design context across the entire project lifecycle.

Step 4 — Use Agent Manager to Build in Parallel

Switch to Manager View and dispatch three agents simultaneously:

Agent 1 — Frontend components:

Read the Stitch MCP project and implement all UI components
from the dashboard screens. Use DESIGN.md for exact colors,
typography, and spacing. Create reusable components in
src/components/. Use shadcn/ui as the base component library.

Agent 2 — Auth system:

Implement authentication using Supabase Auth.
Create login page matching the Stitch login screen design.
Set up middleware to protect /dashboard routes.
Add session handling with @supabase/ssr.

Agent 3 — Database and API routes:

Design the PostgreSQL schema for a project management SaaS.
Include tables for users, projects, tasks, and team members.
Create Supabase migrations. Build Route Handlers for CRUD
operations on projects and tasks.

All three agents run in parallel. Each generates Artifacts — task lists, implementation plans, and progress summaries you can review without reading raw code. Leave feedback directly on an Artifact and the agent incorporates it without stopping.

Step 5 — Browser Subagent Tests Your UI

Once your frontend is built, prompt the browser agent:

Open the app at localhost:3000.
Navigate through every screen in the Stitch design.
Verify each screen matches the original design.
Check that all navigation between screens works correctly.
Report any visual discrepancies or broken interactions.

The subagent launches Chrome, clicks through your app, takes screenshots, and compares them against your Stitch designs. Failures get flagged as Artifacts with annotated screenshots — you review and the agent fixes.

Step 6 — Add Stripe Billing

The subagent launches Chrome, clicks through your app, takes screenshots, and compares them against your Stitch designs. Failures get flagged as Artifacts with annotated screenshots — you review and the agent fixes.

Step 6 — Add Stripe Billing

Read the Stitch settings screen design.
Implement a billing section using Stripe subscriptions.
Create a /api/webhooks/stripe route handler.
Add a pricing page matching the Stitch design.
Use the existing Supabase subscriptions table pattern.
Run the test suite after implementation.

Step 7 — Deploy to Vercel

npm install -g vercel
vercel deploy
vercel env add NEXT_PUBLIC_SUPABASE_URL
vercel env add NEXT_PUBLIC_SUPABASE_ANON_KEY
vercel env add SUPABASE_SERVICE_ROLE_KEY
vercel env add STRIPE_SECRET_KEY
vercel env add STRIPE_WEBHOOK_SECRET
vercel --prod

Key Features of This Workflow

• No design handoff gap — Stitch MCP means agents implement exactly what was designed, not an approximation
• Parallel agent execution — frontend, auth, and backend build simultaneously in Antigravity's Agent Manager
• Browser testing built in — subagents test your UI in real Chrome before you review anything
• DESIGN.md as shared context — every agent across every session reads the same design system file
• Free stack — Stitch, Antigravity, Supabase free tier, and Vercel hobby plan cost nothing to start
• Self-correcting agents — when tests fail, Antigravity agents diagnose and fix without your intervention

Stitch + Antigravity vs Other SaaS Build Workflows

The MCP connection is the differentiator. Every other workflow in this table requires a manual step between design and code. Stitch and Antigravity eliminate that step entirely.

Limitations to Know Before You Start

Stitch exports HTML/CSS by default. React export exists but is still maturing as of 2026. The Antigravity agent can convert the HTML/CSS to React components — add this to your Agent 1 prompt explicitly.

Antigravity is public preview. It is stable enough for real projects but has rough edges. The recommendation from most experienced users in 2026 is to use Antigravity for building and Cursor as a fallback for precise edits.

Stitch has monthly generation limits. 350 standard generations per month on the free tier. For a focused SaaS build this is sufficient — for heavy daily iteration it can run out. You cannot buy additional credits currently.

Agent context limits on large projects. After significant codebase growth, individual agents may lose context on earlier decisions. Keep your DESIGN.md and a CLAUDE.md-equivalent rules file updated as the project grows — Antigravity supports similar project-level configuration files.

Browser subagent requires Chrome. The UI testing feature is Chrome-specific. If your target users use Safari or Firefox, add manual cross-browser testing after the subagent passes.

My Take — Why This Workflow Changes the Mental Model

I have been thinking about the Stitch and Antigravity combination for a while and the part that actually excites me is not the speed — it is what it does to the role of the developer.

The actual reason most solo founders never ship is not that they cannot code. It is that the distance between a clear idea in their head and something a user can click is enormous — and most of that distance is not coding, it is designing, translating, wiring, testing. Stitch collapses the design phase to minutes. The MCP connection to Antigravity collapses the translation phase. The browser subagent collapses the testing phase.

What is left is product thinking. What should the app actually do? What does the user journey feel like? What is the pricing model? Those are the questions that determine whether a SaaS succeeds — and none of them are things an agent can answer for you.

The worst way to use this workflow is to describe a vague product idea, let the agents build something, and ship it. The best way is to think deeply about what you are building first, use Stitch to validate the information architecture visually before a line of code is written, and then use Antigravity to execute the implementation you have already thought through.

The future of this is going to be agents that span the entire pipeline — from user research to deployed product. We are not there yet. But Stitch plus Antigravity is the clearest preview of what that future looks like. Two tools, one MCP connection, and you go from idea to working SaaS in days instead of months.

Frequently Asked Questions

Is Google Antigravity actually free?
Antigravity is free in public preview with generous rate limits on Gemini 3 Pro. Paid plans exist at $20/month Pro and $249.99/month Ultra for higher usage. For building an MVP the free tier is sufficient — most developers hit rate limits only during heavy multi-agent sessions running many parallel tasks simultaneously.

Does the Stitch MCP connection work with tools other than Antigravity?
Yes. The Stitch MCP server is a standard Model Context Protocol implementation. It works with any MCP-compatible client — Cursor, Claude Code, and other tools that support MCP servers. Antigravity is the most natural pairing because of the direct export button in Stitch's UI, but the MCP connection itself is tool-agnostic.

Can Antigravity deploy my app or do I still need Vercel?
Antigravity builds and tests locally. It does not handle deployment. You still need Vercel, Railway, or another hosting provider for production deployment. The agent can write your vercel.json configuration and run the Vercel CLI commands — but the actual deployment infrastructure lives outside Antigravity.

How is Antigravity different from Cursor for this workflow?
The key difference is the Agent Manager — Antigravity lets you run multiple agents in parallel across different parts of the codebase simultaneously. Cursor's agent mode is sequential. For a SaaS build where frontend, backend, and auth can be developed in parallel, Antigravity's multi-agent execution cuts build time significantly compared to sequential agent tasks in Cursor.

What happens when Stitch generates the wrong UI and I need to fix it?
Iterate in Stitch first before connecting to Antigravity. Use the infinite canvas to get the design right — add manual edits, generate variants, use voice commands to refine. Once you are happy with the design, connect via MCP. Fixing design problems at the Stitch stage costs nothing. Fixing them after an agent has implemented five screens costs agent credits and time.

Conclusion

Google Stitch and Antigravity are the most complete free SaaS build stack available in 2026. Stitch handles the design phase that used to require a designer or hours in Figma. The MCP connection eliminates the handoff gap. Antigravity's parallel agents build frontend, auth, and backend simultaneously. The browser subagent tests the result before you review anything.

Use this workflow if you are a solo founder who wants to go from idea to working product fast, a developer who wants to skip the design phase without skipping the quality, or a small team that cannot afford separate design and development cycles.

The stack is free. The tools are real. The only thing between your idea and a working SaaS is how clearly you can describe what you want to build.

Related reads: Best AI Coding Tools for Developers in 2026 · How Developers Use AI to Build Apps Faster · How to Create a SaaS with Next.js and Supabase · How to Deploy Next.js on Vercel Step-by-Step