Build Your FirstAI-Powered SaaS
A complete, step-by-step guide to building production-ready AI applications. Learn the exact patterns, tools, and strategies used to ship real products that scale.
What you'll learn: Monorepo setup, AI integration, authentication, payments, deployment, and everything in between.
Quick Navigation
Getting Started: Build Your SaaS Foundation
Ready to build your AI-powered SaaS? Let's walk through setting up everything from scratch. This is the exact foundation used in production applications.
Step 1: Set Up Your Monorepo
Start with a pnpm workspace monorepo. This gives you shared packages, consistent tooling, and simplified dependency management from day one.
💡 Why monorepo? Shared types, reusable components, and one command to build everything. It scales with your team.
Step 2: Configure Supabase for Backend
Supabase gives you PostgreSQL, authentication, and real-time features in one package. Set up your project and configure environment variables.
Create Tables
Use Supabase SQL editor to create your data models. Enable Row-Level Security (RLS) on all tables.
Enable Auth
Enable email/password authentication in Supabase dashboard. Add OAuth providers if needed.
Step 3: Integrate AI with OpenRouter
Add AI capabilities using the Vercel AI SDK and OpenRouter. This gives you access to multiple AI models through a unified API.
💡 Why OpenRouter? Access to 200+ AI models through one API. Switch models without code changes. Cost optimization built-in.
Step 4: Set Up Stripe for Payments
Add payment processing with Stripe. Create products, set up pricing, and configure webhooks for subscription management.
⚠️ Important: Always verify webhook signatures before processing events. Never skip this, even in development.
Step 5: Start Development
With everything configured, start your development server and begin building your features.
Next steps: Build your core features, implement authentication flows, add payment processing, and iterate based on user feedback.
Building AI-Powered Features
Now that your foundation is set, let's dive into integrating AI capabilities. I'll show you how to add streaming responses, control costs, and structure your prompts for production use.
01. Streaming with Vercel AI SDK
The Vercel AI SDK makes streaming AI responses incredibly simple. It handles Server-Sent Events (SSE), automatic reconnection, and error handling so you don't have to.
💡 Pro tip: The SDK automatically handles network reconnection. If a user's connection drops mid-stream, it will resume where it left off.
02. Rate Limiting & Cost Control
AI costs can spiral quickly. Implement two-tier rate limiting: IP-based limits prevent abuse, while per-user limits control individual usage patterns.
IP-Based Limits
Prevent spam from single sources using sliding window algorithms with Redis-backed storage.
User-Based Limits
Control costs per user account. Track usage across sessions and implement tiered limits based on subscription status.
⚠️ Critical: Always implement rate limiting before going to production. A single user can easily rack up hundreds of dollars in AI costs without limits.
03. Prompt Engineering Best Practices
The quality of your AI responses depends entirely on your prompts. Here's the structure I've found works best in production:
Role Definition
"You are an expert portfolio reviewer with 10 years of experience in tech hiring..."
Context Injection
Provide relevant data, user history, and specific constraints for the task.
Response Guidelines
Specify format (JSON, markdown), tone (professional, casual), and output structure.
💡 Pro tip: Test your prompts with edge cases. What happens if the user provides no data? What if the data is malformed? Handle these gracefully.
04. Structured Widget Rendering
Want your AI to trigger UI components? Use command delimiters. This pattern lets the AI request specific data displays while maintaining conversational flow.
💡 Use case: Perfect for portfolio sites where AI can trigger project cards, skill visualizations, or timeline widgets mid-conversation.
Architecture Patterns That Scale
Building a SaaS that lasts requires solid architecture. Let me share the patterns I've used in production that scale with your team and your users.
01. Monorepo with pnpm Workspaces
Monorepos aren't just for big companies. They give you shared packages, consistent tooling, and simplified dependency management from day one. I use pnpm workspaces for efficient linking and fast installs.
Benefits
- • Shared type definitions
- • Reusable UI components
- • Consistent tooling
- • Single source of truth
Best Practices
- • Use workspace protocol
- • Semantic versioning
- • Clear package boundaries
- • Turbopack for builds
💡 Pro tip: Start with a monorepo even for small projects. The overhead is minimal, and you'll thank yourself when you need to add a second app or shared package.
02. Component Design Systems
Don't rebuild the wheel. Build a component library with Radix UI primitives, Tailwind CSS, and Framer Motion. This creates consistent UI patterns across your application and speeds up development.
Primitives First
Start with Radix UI for accessible, unstyled components. Add styling with Tailwind CSS for consistency. This combo gives you accessibility out of the box.
Compound Components
Use compound component patterns for complex UI elements (dialogs, dropdowns, menus). This makes your components more composable and easier to use.
Animation System
Framer Motion for smooth animations. Keep animations subtle and purposeful - never gratuitous. Animations should guide attention, not distract.
💡 Pro tip: Extract common patterns early. If you find yourself copying and pasting component code, it's time to create a reusable component in your design system.
03. API Design Patterns
Good API design makes your frontend code cleaner and your backend more maintainable. Design RESTful APIs with clear resource boundaries and proper HTTP semantics.
💡 Principles: Use nouns for resources, HTTP verbs for actions, plural nouns for collections, and consistent response envelopes with error handling.
Authentication & Security
Security isn't optional. Let me show you how to implement robust authentication with Supabase, row-level security, and webhook verification patterns that keep your users safe.
01. Supabase Row-Level Security
Row-Level Security (RLS) is your first line of defense. It enforces data access rules at the database level, so even if someone bypasses your application logic, they can't access data they shouldn't.
Why RLS Matters
Database-level security means even API bugs can't leak data. It's defense in depth.
Best Practices
Enable RLS on all tables. Never rely solely on application-level checks.
⚠️ Critical: Never trust client-side data validation. Always enforce rules at the database level with RLS policies.
02. Webhook Signature Verification
Webhooks are powerful but dangerous if not verified. Always verify signatures before processing events to prevent attackers from sending fake events to your endpoints.
⚠️ Critical: Never skip signature verification, even in development. Use different webhook secrets for different environments.
03. Security Headers
Set comprehensive security headers to protect against common vulnerabilities. Configure these in Next.js middleware or next.config.
HSTS
Force HTTPS connections with max-age and includeSubDomains to prevent protocol downgrade attacks.
CSP
Content Security Policy to prevent XSS attacks with strict allowlists for scripts, styles, and other resources.
X-Frame-Options
Prevent clickjacking attacks with SAMEORIGIN or DENY to control frame embedding.
Referrer-Policy
Control referrer information leakage with strict-origin-when-cross-origin for privacy.
Payment Integration
Monetizing your SaaS with Stripe doesn't have to be complicated. Let me show you how to handle subscriptions, webhooks, and billing with proper API version handling.
01. Webhook Signature Verification
Always verify webhook signatures before processing events. This is your primary defense against fraudulent payment events.
⚠️ Critical: Never skip verification - even in development. Use different webhook secrets for different environments.
02. Idempotency Checks
Stripe may retry webhook events. Implement idempotency to prevent duplicate processing of the same event.
💡 Why it matters: Without idempotency, you could charge users multiple times or create duplicate database records.
03. API Version Handling
Stripe API versions have breaking changes. The Dahlia API version moved subscription fields to items.data[]. Handle this gracefully.
💡 Best practice: Always check for field existence and provide fallbacks. Document API version requirements in your code.
Deployment Strategy
Shipping your SaaS to production requires more than just pushing code. Let me share the deployment patterns I use for reliable, automated releases.
01. NPM Package Publishing
If you're building reusable packages, publish them to npm with semantic versioning and trusted publishing. Use Changesets for automated version management.
Trusted Publishing
Use npm OIDC authentication for secure CI/CD without managing tokens.
Semantic Versioning
Follow semver strictly: major for breaking changes, minor for features, patch for fixes.
💡 Pro tip: Configure trusted publishing in npm package settings. No more managing tokens or secrets in CI.
02. CI/CD Pipeline
Automate your deployment with GitHub Actions. Run tests, build your application, and deploy to production automatically on merge to main.
💡 Best practice: Run tests and linting in CI before deployment. Catch issues before they reach production.
03. Environment Management
Manage environment variables securely across development, staging, and production. Never commit secrets to git.
Development
Use .env.local for local development. Add to .gitignore.
Production
Set environment variables in your hosting platform (Vercel, Railway, etc.).
Ready to Start Building?
You now have everything you need to build a production-ready AI SaaS. Start with the Getting Started section above and work your way through each topic.
🎯 Your First Steps
- • Set up your monorepo with pnpm
- • Configure Supabase for backend
- • Integrate AI with OpenRouter
- • Add Stripe for payments
🚀 Going to Production
- • Implement RLS policies
- • Set up CI/CD pipeline
- • Configure environment variables
- • Monitor and iterate
Remember: Start small, iterate fast, and always prioritize security. These patterns have been tested in production and will scale with your application.
Built with real-world production experience. Patterns tested at scale.