Backend and platform engineering experience across product-critical systems.
Software Architect / Backend Systems / Product Architecture
I design and build product-grade systems for money, data, and operational scale.
I am James Hay, a senior backend engineer and software architect focused on monetization, billing, SaaS platforms, data systems, and the architectural seams where product decisions become durable software.
Useful where product complexity meets system complexity.
Comfortable with recurring revenue, account lifecycle, billing, and operational data flows.
Pragmatic architecture, service boundaries, integration contracts, and maintainable delivery.
What I work on
Architecture for software that has to survive contact with customers.
Selected work
PaidToday Kit
A solo product build for overdue invoice recovery: structured intake, Stripe Checkout, Supabase persistence, entitlement modeling, AI generation, deterministic fallback, and copyable customer-facing artifacts.
Read the case studyMonetization and billing systems
Subscription models, invoices, account states, entitlement checks, pricing rules, lifecycle events, and the operational workflows around revenue systems.
Backend and data platforms
API design, durable data modeling, Kafka/event-driven flows, PostgreSQL-backed systems, and the boring reliability work that keeps product surfaces trustworthy.
Product architecture
Translating fuzzy product intent into technical direction: boundaries, invariants, failure modes, delivery slices, and systems that can evolve without constant heroics.
Positioning
A systems engineer with product judgment.
I am most valuable when the problem is not merely "write the code," but decide what shape the system should take, what guarantees it must preserve, and how the implementation can move forward without collapsing under ambiguous requirements.
My bias is toward clear contracts, explicit tradeoffs, incremental delivery, and architecture that earns its complexity. Good systems should make the next decision easier, not just make the current deadline possible.
Working principles
The operating model.
Make the model explicit
Name the entities, states, transitions, constraints, and failure modes before the system hides them.
Prefer boring reliability
Use familiar tools well. Complexity should be justified by the product or operational need.
Design for change
Boundaries should support iteration. A good architecture leaves room for new information.
Close the loop
Architecture is not a diagram. It is validated through working software, feedback, and production reality.
Contact
For roles, consulting, architecture reviews, or product-system work.
The best starting point is a concise note with the product context, the system pressure, and what needs to become clearer.