AI SaaS Starter Kit

A production-ready, multi-tenant AI SaaS boilerplate built with NestJS, Next.js 15, and Anthropic Claude. Includes authentication, usage metering, plan limits, team management, and Stripe billing — all wired up and ready to customize.

Features

• Multi-tenant architecture — Organization → Member → User with role-based access (owner / admin / member)
• Claude AI streaming — Real-time SSE chat powered by claude-sonnet-4-5 via Anthropic SDK
• Usage metering — Token counting per conversation, monthly aggregate tracking, plan limit enforcement
• Plan tiers — Free (50K tokens), Pro (500K), Enterprise (5M); enforced at the API layer
• Stripe billing — Checkout sessions, customer portal, webhook handler; gracefully degrades when Stripe is not configured
• JWT auth — Access + refresh tokens, bcrypt password hashing, organization context embedded in JWT
• BullMQ email queue — Ready-to-extend transactional email via Nodemailer
• Next.js 15 App Router — Dark-themed dashboard: chat, team, billing, usage overview

Tech Stack

Layer	Technology
Backend	NestJS 11, TypeORM, PostgreSQL 15
AI	Anthropic Claude SDK (@anthropic-ai/sdk) with streaming
Auth	JWT (access + refresh), bcrypt, Passport
Billing	Stripe (graceful no-op when unconfigured)
Frontend	Next.js 15 App Router, TypeScript, Tailwind CSS
State	Zustand with persistence
CI	GitHub Actions

Architecture

Browser → Next.js (App Router) → NestJS API → PostgreSQL
                                      ↓
                               Anthropic Claude
                                      ↓
                               Usage Tracking DB

Quick Start

# 1. Start PostgreSQL
cd backend && docker compose up -d

# 2. Configure backend
cp .env.example .env
# Add your ANTHROPIC_API_KEY — Stripe keys are optional (billing degrades gracefully)
npm install && npm run start:dev

# 3. Start frontend
cd ../frontend
echo "NEXT_PUBLIC_API_URL=http://localhost:3003" > .env.local
npm install && npm run dev

• API: http://localhost:3003/api (Swagger docs)
• Frontend: http://localhost:3001

API Endpoints

Auth

Method	Path	Description
POST	/auth/register	Register + create organization
POST	/auth/login	Login
POST	/auth/refresh	Refresh tokens

AI

Method	Path	Auth	Description
POST	/ai/chat	JWT	Stream chat (SSE)
GET	/ai/conversations	JWT	List conversations
GET	/ai/conversations/:id/messages	JWT	Get messages
DELETE	/ai/conversations/:id	JWT	Delete conversation

Usage

Method	Path	Auth	Description
GET	/usage/me	JWT	Monthly token usage
GET	/usage/me/limit	JWT	Check current plan limit

Organizations

Method	Path	Auth	Description
GET	/organizations/me	JWT	Get org details
GET	/organizations/me/members	JWT	List members
DELETE	/organizations/me/members/:id	JWT	Remove member
PATCH	/organizations/me/members/:id/role	JWT	Update member role

Billing

Method	Path	Auth	Description
POST	/billing/checkout	JWT	Create Stripe checkout session
POST	/billing/portal	JWT	Open Stripe billing portal
POST	/billing/webhook	—	Stripe webhook handler

Plan Limits

Plan	AI Tokens/Month	Members	Conversations
Free	50,000	3	10
Pro	500,000	20	Unlimited
Enterprise	5,000,000	Unlimited	Unlimited

Environment Variables

Backend

PORT=3003
DB_HOST=localhost
DB_PORT=5435
DB_USERNAME=postgres
DB_PASSWORD=postgres
DB_DATABASE=ai_saas
JWT_SECRET=...
JWT_EXPIRES_IN=15m
JWT_REFRESH_SECRET=...
JWT_REFRESH_EXPIRES_IN=7d
ANTHROPIC_API_KEY=sk-ant-...
STRIPE_SECRET_KEY=sk_test_...   # Optional — billing degrades gracefully
STRIPE_WEBHOOK_SECRET=whsec_... # Optional
STRIPE_PRICE_PRO=price_...      # Optional
STRIPE_PRICE_ENTERPRISE=price_...
SMTP_HOST=...
SMTP_PORT=465
SMTP_USER=...
SMTP_PASS=...

Frontend

NEXT_PUBLIC_API_URL=http://localhost:3003
NEXT_PUBLIC_STRIPE_PRICE_PRO=price_...      # Optional
NEXT_PUBLIC_STRIPE_PRICE_ENTERPRISE=price_... # Optional

Testing

cd backend && npm test
# 8 tests: AuthService (ConflictException, register flow, bad password, bad refresh token)
#          OrganizationsService (ForbiddenException, NotFoundException, successful remove)
#          app.controller (hello world)