Why pre-screen API developers before the technical interview
Once somebody integrates, every decision becomes permanent. A field name, an error format, a default that turns out to be wrong: all of it is now somebody else's dependency, and changing it breaks their system. Developers worth hiring have made a breaking change carefully and lived with the consequences. A short screen asks how they handled one.
What actually matters when screening API Developer candidates
- 01
Technical proficiency
Check fluency in REST and GraphQL design: OpenAPI/Swagger specs, versioning strategy, OAuth2 and JWT flows, pagination, idempotency keys, and gateway config in Kong, Apigee or AWS API Gateway.
- 02
Systems and trade-offs
Probe how they handled rate limiting, caching headers, backward compatible schema changes, and breaking-change deprecation windows for consumers they did not control.
- 03
Evidence and rigour
Test their evidence habits: contract tests with Pact, Postman or k6 load runs, p95 latency and error-rate SLOs, and how they traced a production 5xx spike.
- 04
Collaboration and communication
Assess how they support consumers: developer docs, changelogs, sandbox environments, and handling integration questions from partner or internal client teams.
Pre-screening questions to ask API Developer candidates
12 questions grouped by what they test. Ask the same set in every screen and score answers on a consistent scale, or send them as an async video screen and compare answers side by side.
Interfaces they support
3 questions01Have you developed an interface from scratch, and what did that involve?
Listen forDesign decisions they owned including resource modelling, with consumers they had to support.
Endpoints added to an existing design only, or no experience supporting integrators.
02Can you describe a complex interface you have worked with?
Listen forComplexity explained in terms of state or workflow, with what made it difficult to consume.
Complexity described as endpoint count, or no view on what made it awkward to use.
03Can you discuss designing an interface for a high-load system?
Listen forPagination, caching and rate limits designed in, with load characteristics understood beforehand.
Scale addressed after problems appeared, or unbounded responses returned by default.
Deliberate design
4 questions04How do you handle versioning?
Listen forA versioning strategy chosen deliberately, with deprecation communicated and a migration path given.
Breaking changes shipped without versioning, or consumers discovering changes when they break.
05What is your understanding of idempotent operations in interface design?
Listen forIdempotency explained accurately, with retry safety designed for operations that create resources.
Idempotency confused with safety, or duplicate creation on retry not considered.
06What is your approach to error handling?
Listen forConsistent error shapes with useful codes, so consumers can distinguish and handle each case.
Errors returned with a success status, or messages that consumers cannot act on.
07How would you design an interface for scalability?
Listen forStatelessness, caching and asynchronous patterns applied where the workload actually requires them.
Scalability described as adding servers, or long operations handled synchronously.
Secured properly
3 questions08Can you explain your approach to securing an interface?
Listen forAuthentication, authorisation per resource and input validation are all handled as standard.
Authorisation checked only at the gateway, or object access not verified per request.
09Do you have experience with delegated authorisation protocols?
Listen forFlows understood with token scope and expiry handled correctly for the client type.
Flows confused, or long-lived tokens issued with broad scope by default.
10How do you manage keys and other sensitive configuration?
Listen forSecrets held outside code with rotation possible, and access scoped per environment.
Keys committed to repositories, or the same credentials used across environments.
Documented and tested
2 questions11What is your experience with interface documentation?
Listen forDocumentation generated or maintained alongside the code, with working examples for consumers.
Documentation written once and left to drift, or examples that no longer work.
12What is your experience with testing, and which tools do you use?
Listen forContract and integration tests run automatically, catching any breaking changes before release.
Testing done manually with a client tool, or breaking changes found by consumers.
How to score responses
Score every candidate on the same four criteria immediately after the screen. At this stage you are shortlisting for panel interviews, not making the final call.
Technical proficiency
35%5Names concrete spec decisions, explains token refresh and idempotent retries, and shows endpoints they authored end to end.
Systems and trade-offs
25%5Weighs consumer impact against internal cleanliness, describes a deprecation timeline they ran, and explains cache and throttle choices with numbers.
Evidence and rigour
25%5Cites latency and error budgets before and after their changes, and points to contract or load tests that caught a regression.
Collaboration and communication
15%5Describes documentation or a sandbox they built, and gives a case where partner feedback reshaped an endpoint design.
Once somebody integrates, every field name is a permanent promise. A one-way video screen asks about the breaking change.
Try it on HirevireScreening FAQ
Process basics
How long should a pre-screening round for this role take?
Fifteen minutes across eight to ten questions, answered async. Enough to establish interfaces they built and support, test their design thinking, and check security and documentation.
What should the screen establish beyond building endpoints?
Whether they have supported consumers. Designing an interface is easy until real integrators depend on it and every change has to be communicated and versioned.
Evaluating answers
What is the strongest signal when screening this role?
How they made a breaking change. Developers who support consumers describe versioning, deprecation notice and migration help. Anyone who has never had to has not maintained an interface.
How do I judge their security practice?
Ask how authentication and secrets are handled. Real answers cover token scope, expiry and storage outside code. Anyone whose keys live in a repository has already leaked one.
Go deeper on this role
Sanat has been hiring since 2012 and watching the recruitment industry change up close ever since, and turned that screening process into Hirevire's video screening platform. LinkedIn
