Next.js SaaS Starter : Le guide complet pour lancer votre SaaS

npx create-next-app@14 mon-saas \
  --typescript --tailwind --eslint --app \
  --src-dir --import-alias "@/*"

cd mon-saas

# Installer les dépendances essentielles
npm install prisma @prisma/client next-auth
npm install stripe @stripe/stripe-js
npm install zod react-hook-form
npm install @neuraapi/sdk

npx prisma init --datasource-provider postgresql

// prisma/schema.prisma
generator client {
  provider = "prisma-client-js"
}

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

model User {
  id             String         @id @default(cuid())
  email          String         @unique
  name           String?
  password       String
  plan           String         @default("free")
  stripeCustomerId String?      @unique
  apiKey         String         @unique @default(cuid())
  createdAt      DateTime       @default(now())
  updatedAt      DateTime       @updatedAt
  projects       Project[]
  subscription   Subscription?
}

model Project {
  id        String   @id @default(cuid())
  name      String
  userId    String
  user      User     @relation(fields: [userId], references: [id])
  createdAt DateTime @default(now())
}

model Subscription {
  id                 String   @id @default(cuid())
  userId             String   @unique
  user               User     @relation(fields: [userId], references: [id])
  stripeSubscriptionId String @unique
  status             String
  plan               String
  currentPeriodEnd   DateTime
}

// src/lib/auth.ts
import NextAuth from 'next-auth'
import CredentialsProvider from 'next-auth/providers/credentials'
import { prisma } from './db'
import bcrypt from 'bcryptjs'

export const { handlers, auth, signIn, signOut } = NextAuth({
  providers: [
    CredentialsProvider({
      credentials: {
        email: { label: 'Email', type: 'email' },
        password: { label: 'Mot de passe', type: 'password' },
      },
      async authorize(credentials) {
        const user = await prisma.user.findUnique({
          where: { email: credentials?.email as string },
        })
        if (!user) return null
        const valid = await bcrypt.compare(
          credentials?.password as string, user.password
        )
        if (!valid) return null
        return { id: user.id, email: user.email, name: user.name }
      },
    }),
  ],
  session: { strategy: 'jwt' },
  pages: { signIn: '/login' },
})

// src/app/dashboard/layout.tsx
import { auth } from '@/lib/auth'
import { redirect } from 'next/navigation'
import Sidebar from '@/components/dashboard/Sidebar'

export default async function DashboardLayout({
  children,
}: {
  children: React.ReactNode
}) {
  const session = await auth()
  if (!session) redirect('/login')

  return (
    <div className="flex min-h-screen">
      <Sidebar user={session.user} />
      <main className="flex-1 p-8">{children}</main>
    </div>
  )
}

// src/app/api/stripe/checkout/route.ts
import { NextRequest, NextResponse } from 'next/server'
import { auth } from '@/lib/auth'
import Stripe from 'stripe'

const stripe = new Stripe(process.env.STRIPE_SECRET_KEY!)

const PLANS = {
  starter: { priceId: 'price_xxx', name: 'Starter' },
  pro: { priceId: 'price_yyy', name: 'Pro' },
  enterprise: { priceId: 'price_zzz', name: 'Entreprise' },
}

export async function POST(req: NextRequest) {
  const session = await auth()
  if (!session?.user) {
    return NextResponse.json({ error: 'Non autorisé' }, { status: 401 })
  }

  const { plan } = await req.json()
  const selectedPlan = PLANS[plan as keyof typeof PLANS]
  if (!selectedPlan) {
    return NextResponse.json({ error: 'Plan invalide' }, { status: 400 })
  }

  const checkoutSession = await stripe.checkout.sessions.create({
    mode: 'subscription',
    payment_method_types: ['card'],
    customer_email: session.user.email!,
    line_items: [{ price: selectedPlan.priceId, quantity: 1 }],
    success_url: `${process.env.NEXT_PUBLIC_APP_URL}/dashboard?success=true`,
    cancel_url: `${process.env.NEXT_PUBLIC_APP_URL}/pricing?canceled=true`,
    metadata: { userId: session.user.id, plan },
  })

  return NextResponse.json({ url: checkoutSession.url })
}

// src/lib/ai.ts
import { NeuraAPI } from '@neuraapi/sdk'

const ai = new NeuraAPI(process.env.NEURA_API_KEY!)

export async function generateContent(prompt: string, userId: string) {
  // Vérifier le quota utilisateur
  const credits = await checkCredits(userId)
  if (credits <= 0) {
    throw new Error('Crédits épuisés. Passez au plan supérieur.')
  }

  const result = await ai.generate({
    prompt,
    maxTokens: 1000,
  })

  // Déduire un crédit
  await consumeCredit(userId)

  return result.content
}

# Installer Vercel CLI
npm i -g vercel

# Déployer en staging
vercel

# Configurer les variables d'environnement
vercel env add DATABASE_URL
vercel env add NEXTAUTH_SECRET
vercel env add STRIPE_SECRET_KEY
vercel env add STRIPE_WEBHOOK_SECRET
vercel env add NEURA_API_KEY

# Déployer en production
vercel --prod