POS SaaS — FastAPI + PostgreSQL

Multi-tenant Point of Sale backend supporting retail and restaurant use cases.

Stack

• API: FastAPI (async)
• DB: PostgreSQL 16 via SQLAlchemy 2.0 (async)
• Migrations: Alembic
• Auth: JWT (python-jose)
• Task queue: Celery + Redis
• Payments: Stripe Terminal + Stripe Online
• Containerization: Docker + docker-compose

Quick Start

# Copy env and edit values
cp .env.example .env

# Start all services
docker compose up -d

# Run migrations
docker compose exec api uv run alembic upgrade head

# API docs
open http://localhost:8000/docs

Tenant Isolation

Row-level isolation: every table has tenant_id (FK → tenants). All queries in services and endpoints filter by tenant_id derived from the JWT. No cross-tenant data leakage is possible without a compromised token.

API Structure

POST /api/v1/tenants/register     Register new tenant + owner
POST /api/v1/auth/login           Get JWT token
GET  /api/v1/products/            List products (tenant-scoped)
POST /api/v1/products/            Create product (admin/owner)
POST /api/v1/orders/              Place order (any authenticated user)
GET  /api/v1/orders/{id}          Get order details

Multi-tenant Data Model

Tenant
  └── Locations (branches)
  └── Users (owner / admin / manager / cashier)
  └── Products → Categories
       └── Orders → OrderItems
            └── Payments