Business Logic
Business logic is the set of product-specific rules that decides what may happen, in what order, and with what consequence. Express important rules once in a testable backend boundary rather than scattering them across screens and integrations.
What You Will Be Able to Decide
- Explain business logic in product and business terms.
- Apply this decision: Express important rules once in a testable backend boundary rather than scattering them across screens and integrations.
- Recognise this material risk: different entry points apply different versions of the same commercial rule.
- Ask a consultant for evidence rather than reassurance.
A founder is reviewing how the product will enforce rules and respond when a request does not go to plan.
Business logic is the set of product-specific rules that decides what may happen, in what order, and with what consequence.
A consultant can recommend and implement the technical approach. The founder still needs to decide which outcome matters, which risk is acceptable, and what evidence is sufficient.
The Practical Question
A founder is reviewing how the product will enforce rules and respond when a request does not go to plan.
The immediate question is business logic. The technical label matters only because it changes a product decision, a responsibility, or the evidence required before launch.
Technical term
Business Logic
Business logic is the set of product-specific rules that decides what may happen, in what order, and with what consequence.
Treat it like a clause in a commercial agreement: its value comes from making expectations and consequences clear, not from sounding formal.
What a Sound Approach Establishes
Start with the product consequence, then choose the simplest technical treatment that protects it. A longer tool list is not a stronger plan.
For this decision, the useful standard is that important rules hold for valid, invalid, repeated, and unauthorised requests.
- Make the decision explicit: Express important rules once in a testable backend boundary rather than scattering them across screens and integrations.
- Ask what evidence would show that the chosen approach works.
- Name the person or provider responsible when the approach fails.
- Record the result in the backend proposal and operational acceptance criteria.
A Decision Framework
Express important rules once in a testable backend boundary rather than scattering them across screens and integrations.
The principal risk is that different entry points apply different versions of the same commercial rule. This does not require the most expensive possible solution. It requires the consequence to be understood and the control to match it.
- Describe the user or business outcome that must be protected.
- Identify the most credible failure and its consequence.
- Compare the simplest adequate approach with one realistic alternative.
- Set a review point for when the decision may need to change.
What Confidence Should Be Based On
Warning Signs
- Nobody can explain how business logic changes a user or business outcome.
- The proposal does not address this risk: different entry points apply different versions of the same commercial rule.
- The only evidence is a successful demonstration of the easiest path.
- The decision has no named owner, boundary, or review point.
- A provider-specific feature is being mistaken for a permanent product requirement.
Questions to Ask a Consultant
- What decision are we making about business logic?
- Which user or business outcome does the recommendation protect?
- How have we reduced or accepted this risk: different entry points apply different versions of the same commercial rule.
- What evidence can I review without relying on the original implementer?
- What is deliberately deferred, and when will it be reconsidered?
- Who owns the accounts, data, documentation, and recovery process?
Key takeaway
Key Takeaway
Business logic is the set of product-specific rules that decides what may happen, in what order, and with what consequence. The founder's job is to make the consequence explicit; the consultant's job is to recommend and demonstrate a proportionate implementation.