Product Engineering Case Studies
How I turn customer problems into reliable software: system design, integrations, applied AI, and the trade-offs behind production decisions.
From problem to production
Designing RBAC, Support Access, and MFA Without Lockouts
How I designed authorization, time-boxed support access, and MFA for a B2B SaaS that runs the proposal-to-billing workflow.
- #auth
- #rbac
- #mfa
- #security
- #nestjs
- #aws-cognito
- #multi-tenant
- #architecture
05 Aug 2026 7 min read 51 views
Designing a Secure REST + MCP API for a Multi-Tenant SaaS
How scoped API keys, shared application services, and request-scoped authentication let one NestJS application support both REST integrations and AI clients.
- #api-design
- #mcp
- #nestjs
- #developer-experience
- #ai-agents
- #typescript
28 Jul 2026 5 min read 231 views
Building a Production QuickBooks Integration, Then an Event-Driven Engine for What Came Next
How I connected Stripe payments to QuickBooks invoices, payments, deposits, and fees, then used those lessons to make future integrations easier to add.
- #integrations
- #quickbooks
- #stripe
- #nestjs
- #accounting
- #multi-tenant
- #architecture
28 Jul 2026 10 min read 69 views