1. API Error Handling advanced

    A shipping aggregator integrates dozens of carriers whose APIs report failures inconsistently - some with HTTP codes, some with 200 and an error body, some with a timeout that means success. How should errors be modelled?

    2 min answer shiprocketerrorsnormalisationambiguity
  2. Event-Driven Integration advanced

    An e-commerce platform integrates order, inventory, payment, logistics and notification through events. Which events should be commands and which should be notifications, and why does confusing them cause outages?

    2 min answer event-drivencommandsnotificationscoupling
  3. Event-Driven Integration advanced

    An event-collection platform routes customer telemetry to hundreds of downstream destinations with different reliability. What delivery guarantees are achievable, and how should destination failures be isolated?

    2 min answer segmentdeliveryisolationdlq
  4. Event-Driven Integration advanced

    An order service publishes events consumed by six teams. Every consumer immediately calls back for order details. What is wrong and what do you change?

    2 min answer eventspayload-designcouplingversioning
  5. Event-Driven Integration advanced

    You operate webhook delivery for 50000 integrators. One endpoint is down for two days. Design the delivery system.

    2 min answer webhooksretriesisolationshopify
  6. GraphQL advanced

    A commerce platform moves its primary API from REST to GraphQL. What genuinely improves for third-party developers, and what new problems does the platform acquire?

    2 min answer graphqlquery-costn-plus-oneapi-design
  7. GraphQL advanced Multiple choice

    A shared API is a bottleneck for four client teams. Does a flexible query language fix it?

    1 min answer graphqlownershipconways-lawcaching
  8. GraphQL intermediate

    A team debates REST and GraphQL for a new public API. What should actually decide it, and what is the operational cost each one imposes?

    2 min answer postmangraphqlrestapi-design
  9. GraphQL advanced

    A team is about to launch a public GraphQL API. What must be in place before it goes live?

    2 min answer graphqlsecurityperformancecaching
  10. gRPC APIs advanced

    A gRPC client fleet calls a backend behind a layer-4 load balancer. After scaling the backend from 10 to 40 pods, the original 10 carry almost all the traffic and the new pods sit idle. Separately, calls have started failing with UNAVAILABLE after quiet periods. Diagnose both.

    3 min answer grpchttp2load balancingkeepalive
  11. gRPC APIs intermediate Multiple choice

    A real-time platform uses gRPC internally and REST externally. Where exactly should the boundary sit, and what belongs at the translation layer?

    2 min answer grpcapi-boundarytranslationgateway
  12. gRPC APIs advanced

    You must remove a field from a protobuf message used by dozens of deployed services. Walk through the safe sequence.

    2 min answer grpcprotobufschema-evolutioncompatibility