whchoi98 SaaS Builder
Core Architecture
- Multi-tenant with tenant isolation at data layer
- Serverless-first: Lambda, API Gateway, DynamoDB
- Integrated billing with Stripe and usage metering
- JWT auth with RBAC
- React + TypeScript frontend with Tailwind CSS
Multi-Tenancy Pattern
- Tenant ID prefix in all DB keys:
${tenantId}#${entityType}#${id} - Lambda authorizer injects tenant context from JWT
- No cross-tenant data access
- Tenant-specific feature flags and quotas
Project Structure
├── frontend/ # React + TypeScript + Tailwind
├── backend/
│ ├── functions/ # Lambda handlers (authorizer, api, billing)
│ ├── lib/ # Business logic
│ └── infrastructure/# IaC (CDK/SAM)
├── schema/ # OpenAPI contracts
└── .kiro/
Lambda Function Pattern
- Extract tenant context from authorizer
- Extract user roles
- Validate parameters
- Check permissions (RBAC)
- Prefix DB operations with tenant ID
- Return proper status codes
- Log with tenant context
Billing Rules
- Integer cents only (never floats):
amount_cents: 1999 - Currency code with every amount
- Stripe for payments, webhook verification, idempotency
- Subscription states: trial, active, past_due, canceled, expired
MCP Servers
- fetch, stripe, aws-knowledge-mcp-server
- awslabs.dynamodb-mcp-server, awslabs.aws-serverless-mcp
- playwright (disabled by default)