Build Only What Differentiates Your MVP, Rent Everything Else

When scoping a minimum viable product, founders face a critical early decision: what to build themselves and what to purchase as a service. The core principle is that only the unique, differentiating feature of a product warrants custom development, while common infrastructure like authentication, payments, and email should be rented from specialist providers. Building commodity capabilities in-house wastes time that could be spent on the actual value proposition, and specialist vendors bring security, compliance, and reliability that small teams cannot replicate. However, renting carries its own risks — vendor lock-in, price changes, and API instability — so dependencies should be isolated behind internal interfaces to limit exposure. The most dangerous trap is mistaking a capability that sits adjacent to the core differentiator for part of it, leading teams to over-build where off-the-shelf solutions already exist.