AI SaaS · Full-Stack
NexaBase
Full-stack SaaS starter with GPT-4o mini streaming chat, Stripe subscription billing, per-user monthly usage quotas, and Supabase Auth.
Next.js 14
FastAPI
LangChain
OpenAI
Supabase
Stripe
Bun
Overview
NexaBase is a production-ready SaaS template that combines authentication, subscription billing, and AI chat into a single deployable package. It demonstrates product engineering — integrating multiple third-party services into a cohesive user experience.
Key Features
- GPT-4o mini streaming chat powered by LangChain and OpenAI API with SSE
- Stripe subscription billing with webhook integration and plan management
- Per-user monthly usage quotas with automatic reset
- Supabase Auth with JWT route protection and row-level security
- Error-logging middleware for production observability
- Deployable via Docker Compose or Vercel + Railway
Architecture
The frontend is built with Next.js 14 using the App Router pattern. The backend API is powered by FastAPI with LangChain for AI orchestration. Supabase handles auth and data, while Stripe manages the billing lifecycle.