Cloud & Complex Systems Interview questions

Integration & API Engineer interview questions

These Integration Engineer interview questions come from our vetting, where 3.4% of applicants pass 5 gates. You get 20 questions with answer hints, a task, red flags and a scorecard.

Updated: October 2026Remote Pro Ai · Cloud & Complex Systems20 questions

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How we assess

Every applicant goes through 5 gates: application, an AI-assisted screen, a live technical assessment scored by a practice lead, a client-fit interview, and reference and credential checks. The questions below come from the live assessment. We score answers on reasoning and trade-offs, not on recalling definitions.

20 technical questions with model-answer hints

Questions 1–⁠10 (role-specific)

  1. How do you version a public API without breaking partners?

    Model-answer hint

    additive changes, versioned paths or headers, deprecation windows, consumer contract tests.

  2. When do you choose events over request-response?

    Model-answer hint

    decoupling, fan-out and async processes versus the need for an immediate answer.

  3. How do you secure partner APIs end to end?

    Model-answer hint

    OAuth client credentials or financial-grade profiles, mTLS, scopes, rate limits, logging.

  4. Walk through mapping an ISO 20022 credit transfer to a legacy payment format.

    Model-answer hint

    field mapping, truncation and enrichment rules, validation, error handling.

  5. A partner sends duplicate requests. How do you handle it?

    Model-answer hint

    idempotency keys, a dedupe store, consistent responses.

  6. What belongs on a developer portal?

    Model-answer hint

    OpenAPI docs, sandbox, onboarding, key management, changelog, SLAs.

  7. How do you design error handling and retries in integrations?

    Model-answer hint

    transient versus permanent errors, backoff, dead-letter queues, alerting.

  8. How does change-data-capture work, and what are the pitfalls?

    Model-answer hint

    log-based capture, schema changes, ordering, the initial snapshot.

  9. How do you monitor integration health?

    Model-answer hint

    throughput, latency and error rates per partner, plus business-level reconciliation.

  10. How do you migrate from an ESB to API-led integration?

    Model-answer hint

    inventory, strangler pattern, prioritised flows, coexistence, decommissioning.

Questions 11–⁠20 (Cloud & Complex Systems core)

  1. How do you make a service idempotent, and why?

    Model-answer hint

    idempotency keys, a dedupe store, safe retries under at-least-once delivery.

  2. How would you set an SLO for a payment API?

    Model-answer hint

    success-and-latency SLI, target from history and business need, an error-budget policy.

  3. Walk through a zero-downtime database migration.

    Model-answer hint

    expand and contract, CDC or dual writes, backfill, verification, flag-controlled cut-over, rollback.

  4. When do you choose event-driven design over synchronous APIs?

    Model-answer hint

    decoupling and fan-out versus harder ordering, consistency and debugging.

  5. How do you keep Terraform safe across many teams?

    Model-answer hint

    versioned modules, locked remote state, reviewed plans, policy-as-code, drift detection.

  6. What belongs in a good post-mortem?

    Model-answer hint

    timeline, impact, contributing factors, blameless tone, actions with owners and dates.

  7. How do you design for data residency across regions?

    Model-answer hint

    data classification, region pinning, in-region keys, replication rules, access logging.

  8. How do you find the cause of a p99 latency regression?

    Model-answer hint

    traces, deploy diff, saturation signals, profiling, slow dependencies.

  9. Tell us about cutting cloud cost without hurting reliability.

    Model-answer hint

    rightsizing, commitments, autoscaling, storage tiering, impact measured before and after.

  10. How do you evolve an API that external partners depend on?

    Model-answer hint

    additive changes, versioning, deprecation windows, consumer contract tests.

Interviewer tip: Ask for a real example after every answer. Strong candidates describe what they built, what broke and what they changed.

Practical task

Design and partly implement an account-information API for an Open Banking scenario: an OpenAPI specification, gateway policies for OAuth 2.0 and rate limiting, a mock adapter mapping a legacy account model, and a short note on versioning and monitoring.

How to run it Share the brief 24 hours ahead or run it live. Ask the candidate to talk through trade-offs as they work; reasoning matters more than a finished artefact.

Red flags our practice leads watch for

  • Treats API security as an API key and nothing more.
  • Has no strategy for versioning or partner communication.
  • Ignores idempotency and retries.
  • Cannot explain how integrations are monitored in production.
  • Universal flag: Vague answers that never reach a concrete system, number or decision the candidate personally owned.

The scorecard we use

Score each dimension 1–⁠4 (1 = no evidence, 2 = partial, 3 = solid, 4 = exceptional):

DimensionWeightWhat a 4 looks like
Technical depth, production judgement and security40%Explains how and why, designs for failure and sensitive data, and knows each tool’s limits
Practical task and problem solving30%Delivers a working solution with tests and documented decisions
Communication and documentation20%Explains clearly to technical and non-technical audiences, in English or Arabic
References and regional context10%References confirm the claimed scope; knows the frameworks and data-residency rules that apply

Pass bar: weighted average of 3.0 out of 4 or higher, with no dimension below 2. The practice lead approves the final result.

Skip the interview loop

Every specialist on our shortlist has already passed this assessment. Working in 4 working days.

Frequently asked questions

Yes. The questions, hints, practical task and scorecard are free to use. They work best when every interviewer scores the same dimensions independently and compares notes afterwards. Ask for a concrete example after each answer, because recalled definitions say little about how someone performs on a live system.

They come from the same live technical assessment, but practice leads rotate and adapt questions so candidates cannot rehearse them. What stays fixed is the scope being tested, the practical task format and the scorecard, which is why the published version is safe to share.

Plan for a technical conversation covering 8 to 10 of the questions, plus the practical task either live or as a short take-home. Use the remaining questions as follow-ups. If you would rather skip the loop, Remote Pro Ai shortlists already-assessed specialists within 48 hours.

Our pass bar is a weighted average of 3.0 out of 4 or higher across the 4 dimensions, with no dimension below 2. Production judgement and security, scored inside the 40% technical dimension, often separate strong candidates from those who interview well but struggle once they own a live system.

The task mirrors the first week of real work in this role and never uses client data. It runs live or as a short take-home of a few hours, and the candidate then explains the trade-offs behind each decision. Reasoning and production habits count for more than a polished final artefact.