SaaS Starter Kit

Reusable utilities and helpers for building SaaS applications with Stripe, Supabase, Next.js, and Prisma.

Overview

This package contains extracted, framework-agnostic utilities from the LaunchKit SaaS boilerplate. It uses dependency injection to eliminate hard-coded configuration imports, making it suitable for distribution as an npm package.

Installation

# As workspace package (current setup)
pnpm add @gobuildlabs/saas-starter-kit@workspace:*

# Future: As published npm package
npm install @gobuildlabs/saas-starter-kit

Modules

🔐 Authentication (Supabase)

Create Supabase clients and authentication helpers.

import { createSupabaseAuth, createAuthHelpers } from '@gobuildlabs/saas-starter-kit/auth';

// Server-side authentication
const supabaseAuth = createSupabaseAuth({
  url: process.env.NEXT_PUBLIC_SUPABASE_URL!,
  anonKey: process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY!,
  serviceRoleKey: process.env.SUPABASE_SERVICE_ROLE_KEY,
});

export async function createServerClient() {
  const cookieStore = await cookies();
  return supabaseAuth.createServerClient(cookieStore);
}

export const supabaseAdmin = supabaseAuth.getAdminClient();

// Auth helpers
const authHelpers = createAuthHelpers({
  defaultRedirect: '/dashboard',
  appUrl: process.env.NEXT_PUBLIC_APP_URL!,
});

const callbackUrl = authHelpers.getValidCallbackUrl('/pricing');
const user = await authHelpers.getUser(supabase);
const isAuth = await authHelpers.isAuthenticated(supabase);

Available Functions:

• createSupabaseAuth(config) - Create server-side Supabase client factory
• createSupabaseClientFactory(config) - Create client-side Supabase singleton
• createAuthHelpers(config) - Create auth helper functions
  • getValidCallbackUrl(url) - Validate callback URLs (prevent open redirects)
  • getUser(supabase) - Get current authenticated user
  • getSession(supabase) - Get current session
  • isAuthenticated(supabase) - Check if user is authenticated

💳 Stripe Integration

Stripe pricing and subscription management utilities.

import { createStripeHelpers } from '@gobuildlabs/saas-starter-kit/stripe';
import { saasConfig } from './config/saas.config';

const stripe = createStripeHelpers(saasConfig);

// Get plan details
const plan = stripe.getPlan('pro');
const paidPlans = stripe.getPaidPlans();
const hasFeature = stripe.hasPlanFeature('pro', 'hdDownloads');

// Trial management
const trialDays = stripe.getTrialDays('pro');
const trialText = stripe.formatTrialPeriod('pro'); // "14-day free trial"
const isInTrial = stripe.isInTrial(subscription);
const daysRemaining = stripe.getTrialDaysRemaining(subscription);

// Customer portal
const portalUrl = await stripe.createCustomerPortalSession(customerId, returnUrl);

// Webhook helpers
const planType = stripe.getPlanTypeByPriceId(priceId);

Available Functions:

• getPlan(planType) - Get plan details
• getPaidPlans() - Get all paid plans
• getAllPlans() - Get all plans including free
• hasPlanFeature(planType, feature) - Check if plan has feature
• getPlanLimit(planType, limitKey) - Get feature limit value
• hasTrial(planType) - Check if plan has trial
• getTrialDays(planType) - Get trial days
• formatTrialPeriod(planType) - Format trial for display
• isInTrial(subscription) - Check if subscription in trial
• getTrialDaysRemaining(subscription) - Get remaining trial days
• createCustomerPortalSession(customerId, returnUrl) - Create Stripe portal session
• getPlanTypeByPriceId(priceId) - Get plan type from price ID (for webhooks)

🔍 SEO & Metadata

Next.js metadata and structured data helpers.

import { createSEOHelpers } from '@gobuildlabs/saas-starter-kit/seo';
import { saasConfig } from './config/saas.config';

const seo = createSEOHelpers(saasConfig);

// Generate page metadata
export const metadata = seo.getSEOTags({
  title: "Pricing",
  description: "Simple, transparent pricing",
  canonicalUrlRelative: "/pricing",
  keywords: ["SaaS", "pricing"],
  twitterCreator: "@yourhandle",
});

// Generate structured data
const orgSchema = seo.getOrganizationSchema();
const websiteSchema = seo.getWebsiteSchema();
const productSchema = seo.getProductSchema({
  name: "Pro Plan",
  description: "Full features",
  price: 19,
  currency: "USD",
});

// Render JSON-LD
const jsonLd = seo.renderStructuredData(orgSchema);

Available Functions:

• getSEOTags(params) - Generate Next.js metadata
• getOrganizationSchema() - Generate organization JSON-LD
• getWebsiteSchema() - Generate website JSON-LD
• getProductSchema(product) - Generate product JSON-LD
• renderStructuredData(data) - Convert schema to JSON string

🗄️ Database (Prisma)

Prisma client with singleton pattern.

import { createPrismaClient } from '@gobuildlabs/saas-starter-kit/db';

export const prisma = createPrismaClient({
  log: ['query'], // Optional: enable query logging
});

// Use as normal
const users = await prisma.user.findMany();

🎨 Utilities

General helper functions.

import { cn } from '@gobuildlabs/saas-starter-kit/utils';

// Merge Tailwind classes (uses clsx + tailwind-merge)
<div className={cn('text-red-500', isActive && 'bg-blue-500')} />

Architecture Pattern: Dependency Injection

All utilities use dependency injection instead of hard-coded imports:

Before (tightly coupled):

import { saasConfig } from '@config/saas.config'; // ❌ Hard-coded

export function getPlan(planType) {
  return saasConfig.stripe.plans[planType];
}

After (dependency injection):

export function createStripeHelpers(config: SaasConfig) {
  return {
    getPlan: (planType) => config.stripe.plans[planType],
    // ... other functions
  };
}

This allows the same code to work with any configuration.

Project Structure

packages/saas-starter-kit/
├── src/
│   ├── lib/
│   │   ├── stripe/
│   │   │   ├── config.ts           # Stripe helpers
│   │   │   └── index.ts
│   │   ├── auth/
│   │   │   ├── supabase-server.ts  # Server-side Supabase
│   │   │   ├── supabase-client.ts  # Client-side Supabase
│   │   │   ├── helpers.ts          # Auth utilities
│   │   │   └── index.ts
│   │   ├── seo/
│   │   │   ├── metadata.ts         # SEO & metadata
│   │   │   └── index.ts
│   │   ├── db/
│   │   │   ├── prisma.ts           # Prisma client
│   │   │   └── index.ts
│   │   └── utils/
│   │       ├── classnames.ts       # cn() utility
│   │       └── index.ts
│   ├── types/
│   │   └── index.ts                # TypeScript types
│   └── index.ts                    # Main entry point
├── dist/                           # Compiled JavaScript + declarations
├── package.json
├── tsconfig.json
└── README.md

Development

# Build the package
pnpm build

# Watch mode (rebuild on changes)
pnpm dev

# Type check
pnpm type-check

# Clean build artifacts
pnpm clean

Migration Status

✅ Completed Extractions:

1. Stripe utilities - lib/stripe-config.ts → src/lib/stripe/config.ts
2. Auth utilities - lib/supabase.ts, lib/supabase-client.ts, lib/auth-helpers.ts → src/lib/auth/
3. SEO utilities - lib/seo.ts → src/lib/seo/metadata.ts
4. Database utilities - lib/prisma.ts → src/lib/db/prisma.ts
5. General utilities - lib/utils.ts → src/lib/utils/classnames.ts

🚧 Future Enhancements:

• API route templates (webhooks, checkout)
• Reusable React components (PricingCard, AuthForm, etc.)
• CLI scaffolding tool (npx @gobuildlabs/saas-init)
• Email templates
• Analytics helpers
• Feature flag system

Backward Compatibility

All web app files maintain backward compatibility through wrapper pattern:

// apps/web/lib/stripe-config.ts
import { createStripeHelpers } from '@gobuildlabs/saas-starter-kit/stripe';
import { saasConfig } from '@config/saas.config';

const stripeHelpers = createStripeHelpers(saasConfig);

// Re-export for backward compatibility - existing code keeps working!
export const {
  getPlan,
  getPaidPlans,
  // ... all functions
} = stripeHelpers;

Package Exports

The package provides modular exports for tree-shaking:

// Main entry
import { createStripeHelpers, createSEOHelpers } from '@gobuildlabs/saas-starter-kit';

// Subpath exports
import { createStripeHelpers } from '@gobuildlabs/saas-starter-kit/stripe';
import { createSupabaseAuth } from '@gobuildlabs/saas-starter-kit/auth';
import { createSEOHelpers } from '@gobuildlabs/saas-starter-kit/seo';
import { createPrismaClient } from '@gobuildlabs/saas-starter-kit/db';
import { cn } from '@gobuildlabs/saas-starter-kit/utils';

// Types
import type { SaasConfig, PricingPlan } from '@gobuildlabs/saas-starter-kit/types';

Type Safety

Full TypeScript support with generated declaration files:

import type {
  SaasConfig,
  PricingPlan,
  PricingPlans,
  StripeHelpers,
  SEOHelpers,
  AuthHelpers,
  SupabaseAuthHelpers,
  SupabaseClientFactory,
} from '@gobuildlabs/saas-starter-kit';

Peer Dependencies

The package lists framework dependencies as optional peers:

• @prisma/client (optional) - Only needed if using DB utilities
• @supabase/ssr (optional) - Only needed if using auth utilities
• @supabase/supabase-js (optional) - Only needed if using auth utilities
• clsx (optional) - Only needed if using cn() utility
• tailwind-merge (optional) - Only needed if using cn() utility
• next (optional) - Only needed if using SEO utilities

This allows consumers to only install what they need.

License

MIT

Next Steps

After completing Phase 1 (extraction), the roadmap includes:

Phase 2: CLI Tool - Create npx @gobuildlabs/saas-init command Phase 3: Template Repository - Minimal starter template Phase 4: Component Library - Extract React components Phase 5: API Route Templates - Parameterized API routes Phase 6: Publishing - Publish to npm registry

Contributing

This package is currently part of a monorepo. To add new utilities:

1. Create new module in src/lib/[module-name]/
2. Use dependency injection pattern (accept config as parameter)
3. Add barrel export in module's index.ts
4. Export from main src/index.ts
5. Add subpath export in package.json
6. Build and test: pnpm build && pnpm type-check
7. Create wrapper in apps/web/lib/ for backward compatibility

Support

For issues and questions, please open an issue on GitHub.