APIs

All interview questions related to APIs

9 Questions
4 Categories
4 Intermediate5 Advanced
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📞 Phone Screen
HTTP Idempotent Methods
Intermediate

Which HTTP methods are idempotent and why does idempotency matter in API design?

2 minPhone
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🔬 Technical Deep Dive
GraphQL vs REST APIs
Advanced

Compare GraphQL and REST APIs in terms of flexibility, performance, and trade-offs.

5 minTechnical
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🔬 Technical Deep Dive
WebSockets vs gRPC Streaming at Scale
Advanced

Contrast WebSockets and gRPC streaming for real-time communication. How do you scale and secure each?

5 minTechnical
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🏗️ System Design
Design a Payment Processing Gateway
Advanced

Design a payment gateway supporting multiple processors, 3-D Secure, refunds, settlements, and PCI concerns.

45 minSystem-Design
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🏗️ System Design
Design a GraphQL Gateway at Scale
Intermediate

Design a federated GraphQL gateway that composes multiple subgraphs, with caching, authorization, and schema evolution.

30 minSystem-Design
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🏗️ System Design
Design an API Gateway / Edge Layer
Advanced

Design a multi-tenant API gateway that handles routing, auth, rate limiting, request/response transformations, canarying, and observability across regions.

45 minSystem-Design
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🏗️ System Design
Design a Secrets Management & KMS Service
Advanced

Design a system for storing secrets and managing encryption keys with rotation, auditing, and fine-grained access control.

45 minSystem-Design
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🔧 Troubleshooting Scenarios
Service Timeout Errors
Intermediate

Multiple services are failing with timeout errors when calling an internal API. How do you approach debugging?

10 minScenario
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🔧 Troubleshooting Scenarios
Thread Pool Exhaustion Causing Latency
Intermediate

Sudden latency spikes correlate with saturated server thread pools. How do you diagnose and remediate safely?

10 minScenario
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