Top three technical risks when becoming a platform and API mitigations

WHAT THIS TESTS: This question evaluates whether you understand that becoming a platform is an architectural boundary change, not a feature launch. Interviewers want to see if you can identify risks that emerge when external developers depend on your infrastructure, and whether you know how to use API-first design to manage those risks before writing backend code.

A GOOD ANSWER COVERS: First, name backward compatibility as the primary risk because external teams cannot refactor on your schedule. Mitigate this with URI or header versioning, semantic versioning discipline, and a published deprecation policy that gives consumers six to twelve months of notice. Second, cite multi-tenant security and abuse because opening your stack turns every endpoint into an attack surface. Mitigate this with OAuth 2.0 or JWT-based authentication, scope-based access control, an API gateway for rate limiting and IP whitelisting, and adherence to OWASP API Security Top 10. Third, highlight domain model leakage, where exposing internal database schemas locks you into legacy structures. Mitigate this by starting with domain modeling to define core resources and relationships, then designing facade APIs in OpenAPI or Swagger before any business logic is written, ensuring the public contract is decoupled from internal implementation.

COMMON WRONG ANSWERS: Treating the API as a thin CRUD wrapper around existing database tables. Suggesting that versioning can be handled later or that breaking changes are acceptable if you email partners. Proposing basic API keys without rate limiting or gateway protection for a public platform. Ignoring developer experience by assuming documentation is an afterthought.

LIKELY FOLLOW-UPS: How would you handle a partner who refuses to migrate off a deprecated v1 endpoint? What is your strategy when the internal domain model must change but the public API cannot? How do you monetize or enforce tiered rate limits without hurting latency? How would you sandbox third-party code if the platform allows custom plugins?

ONE CONCRETE EXAMPLE: Suppose you run a successful payroll application and want to let external HR tools integrate. The risk is that your internal employee table has thirty fields, many of which are compliance-sensitive. Instead of exposing the table, you model a public Worker resource with only five fields in an OpenAPI spec. You version the base path as v1, require OAuth 2.0 with scoped claims, route traffic through an API gateway with one thousand requests per minute rate limits, and publish interactive documentation with request examples. When internal compliance later adds three new database columns, the public Worker contract remains unchanged and external developers are unaffected.

Source: agileseekers.com