Top 50+ AWS API Gateway Interview Questions and Answers (2025 Guide)
In the rapidly evolving world of serverless and cloud-native architectures, AWS API Gateway remains the leading fully managed service for building, deploying, monitoring, and securing APIs at any scale. As of December 2025, recent advancements include fully managed Developer Portals for streamlined API discovery and documentation, MCP proxy support for seamless integration with AI agents through Amazon Bedrock AgentCore, direct private integrations with Application Load Balancers (ALB) for lower latency, response streaming for REST APIs to enable progressive payload delivery, and advanced TLS security policies (including TLS 1.3-only, FIPS-compliant, and Post-Quantum Cryptography options). Combined with VPC Link V2 enhancements and CloudWatch RUM analytics for portals, API Gateway is essential for building secure, high-performance, AI-ready API ecosystems.
This ultimate guide provides over 50 AWS API Gateway interview questions and answers, updated with 2025 features and real-world examples from industries like fintech, healthcare, and e-commerce. Perfect for preparing for roles such as Cloud Architect, DevOps Engineer, or Backend Developer. At clouddevopsjobs.com, we help professionals land top cloud jobs with expert guidance and resources. Ace your interview and boost your career!
What is AWS API Gateway?
AWS API Gateway is a fully managed service that allows developers to create, publish, deploy, and manage RESTful, HTTP, and WebSocket APIs. It serves as the entry point for applications, providing features like traffic management, authorization, monitoring, throttling, and security. In 2025, it includes support for advanced capabilities such as response streaming and MCP proxies for AI integrations, making it ideal for modern microservices and serverless applications. Pricing is usage-based, starting at around $3.50 per million REST requests, with a generous free tier.
Top 50+ AWS API Gateway Interview Questions and Answers
These questions range from basic to expert-level, incorporating the latest 2025 updates and practical scenarios.
- What is AWS API Gateway, and what are its key advantages?
Answer: AWS API Gateway is a managed service for creating, deploying, and managing scalable APIs (REST, HTTP, WebSocket). Key advantages include auto-scaling, integrated security (IAM, Cognito), caching, throttling, and CloudWatch monitoring. Real-World Example: In fintech applications, use it to front Lambda functions with rate limiting to mitigate DDoS risks during high-traffic events. - What API types does API Gateway support?
Answer: – REST APIs: Feature-rich for advanced routing and integrations. – HTTP APIs: Lightweight and cheaper for basic proxy needs. – WebSocket APIs: For real-time bidirectional communication. (gRPC via HTTP/2 in REST/HTTP APIs.) Real-World Example: HTTP APIs for cost-efficient mobile backends; WebSockets for live updates in support chat systems. - Difference between REST APIs and HTTP APIs in API Gateway?
Answer: REST APIs provide extensive features like usage plans, API keys, and custom authorizers but cost more. HTTP APIs are simpler, lower-latency (up to 70% cheaper), with built-in Lambda/JWT support and 2025 additions like enhanced routing. Real-World Example: Opt for HTTP APIs in e-commerce for faster, budget-friendly checkout endpoints. - What are the main integration types in API Gateway?
Answer: – Lambda Proxy: Forwards full request to Lambda. – HTTP Proxy: Routes to external HTTP endpoints. – Mock: Static responses for testing. – AWS Service: Native to services like DynamoDB. (2025: Direct private ALB integration.) Real-World Example: Lambda proxy for querying patient data in healthcare APIs backed by DynamoDB. - How does API Gateway manage authentication and authorization?
Answer: Options include IAM, Cognito User Pools, Lambda authorizers, and native JWT for HTTP APIs. Lambda for custom logic. Real-World Example: Cognito for secure user authentication in social apps, with JWT enforcement on private routes. - What is request/response mapping in API Gateway?
Answer: Uses Velocity Template Language (VTL) to transform data between client and backend, e.g., header additions or format conversions. Real-World Example: Convert JSON requests to XML for integrating with legacy banking systems. - Explain API Gateway caching and configuration.
Answer: Edge-cached responses with customizable TTL (up to 24 hours) and cache keys. Enabled per stage to offload backends. Real-World Example: Cache catalog data in e-commerce to handle traffic surges during promotions. - What are usage plans and API keys?
Answer: Usage plans enforce throttling and quotas per API key (REST APIs only). Keys help track partner usage. Real-World Example: Limit third-party developers to 1000 requests/day in SaaS platforms. - How do you deploy APIs in API Gateway?
Answer: Use stages (dev/prod) and deploy via console/CLI, supporting canary releases. Real-World Example: Canary deployment for gradual rollout of new payment API versions. - What is the Developer Portal feature in API Gateway (2025)?
Answer: Managed portals for API cataloging, auto-generated OpenAPI docs, interactive testing, and CloudWatch RUM analytics. Speeds up developer onboarding. Real-World Example: Self-service portals for partners to discover and subscribe to internal APIs. - Describe API Gateway stages.
Answer: Environments like dev/test/prod with independent settings for throttling, caching, and canary traffic. Real-World Example: Separate staging environment in CI/CD for pre-production validation. - How does API Gateway integrate with AWS Lambda?
Answer: Proxy or custom integrations, sync/async invocation. 2025: Response streaming for large outputs. Real-World Example: Stream image processing results from Lambda in on-demand apps. - What is throttling in API Gateway?
Answer: Method-level (default 1000 req/sec) and account limits with token bucket bursts. Real-World Example: Cap user requests in trading apps to ensure fair usage. - Explain custom domain names.
Answer: Map branded domains (e.g., api.yourcompany.com) with ACM certificates; edge-optimized or regional. Real-World Example: Secure branded domains for patient health portals. - What are private APIs?
Answer: Restricted to VPC via endpoints and resource policies. 2025: Direct ALB private integration. Real-World Example: Internal microservices communication in enterprise VPCs. - How to monitor API Gateway?
Answer: CloudWatch metrics/logs, X-Ray tracing; 2025 RUM for portal insights. Real-World Example: Identify latency issues in supply chain APIs. - What is MCP proxy support (2025)?
Answer: Converts REST APIs to MCP-compatible for AI agents via Bedrock AgentCore, with semantic discovery. Real-World Example: Enable natural language queries on inventory APIs by AI bots. - Explain response streaming (2025).
Answer: Streams large responses progressively for REST APIs with compatible backends. Improves TTFB. Real-World Example: Stream analytics reports in business intelligence tools. - What are the enhanced TLS policies (2025)?
Answer: Support for TLS 1.3-only, PFS, FIPS, and Post-Quantum Cryptography. Real-World Example: PQC for quantum-resistant encryption in sensitive government APIs. - How does API Gateway connect to VPC resources?
Answer: VPC Links (V2 enhanced in recent updates) to ALB/NLB; private APIs. Real-World Example: Public API to private container services via ALB. - What is a Lambda authorizer?
Answer: Custom Lambda to validate tokens and return IAM policies. Real-World Example: Multi-tenant JWT checks in SaaS. - Describe WebSocket APIs.
Answer: Handle connections with routes like $connect/$disconnect; integrate with DynamoDB. Real-World Example: Real-time gaming leaderboards. - Handling CORS in API Gateway?
Answer: Enable in console or mock OPTIONS method. Real-World Example: Support browser requests in single-page applications. - Role of API Gateway in serverless?
Answer: Fronts Lambdas/services with scaling, auth, and management. Real-World Example: Orchestrate media processing workflows. - Explain canary deployments.
Answer: Shift traffic percentages to new versions per stage. Real-World Example: Safe rollout of feature updates. - Usage tiers and quotas?
Answer: Free tier, pay-per-use; higher tiers for bursts. Real-World Example: Enterprise for high-volume IoT data ingestion. - gRPC support?
Answer: Via HTTP/2 protobuf mapping in REST/HTTP APIs. Real-World Example: Efficient ML inference endpoints. - Integration with Amazon Bedrock (2025)?
Answer: MCP proxy for agent tool exposure with semantic search. Real-World Example: AI-driven dynamic routing. - What is VPC Link V2?
Answer: Improved scalability for private integrations to ALB/NLB. Real-World Example: Connect to multiple private backends efficiently. - API versioning strategies?
Answer: Path-based (/v1/), stages, or headers. Real-World Example: Backward-compatible upgrades in payment systems. - Request validation?
Answer: JSON schema models to validate inputs early. Real-World Example: Enforce formats in signup APIs. - Edge-optimized vs. regional endpoints?
Answer: Edge for global low-latency via CloudFront; regional for VPC proximity. Real-World Example: Global apps vs. internal tools. - Handling large payloads?
Answer: Up to 10MB; streaming (2025) or S3 for bigger. Real-World Example: File uploads via presigned URLs. - Custom authorizers vs. Cognito?
Answer: Custom for flexible logic; Cognito for managed OIDC pools. Real-World Example: Federated auth in enterprises. - Developer Portal console features?
Answer: Auto-docs, SDK generation, analytics via RUM. Real-World Example: Interactive sandboxes for partner onboarding. - Securing private integrations?
Answer: Resource policies + VPC endpoints; 2025 direct ALB. Real-World Example: Private database queries. - Throttling and burst handling?
Answer: Steady limits + burst capacity. Real-World Example: Manage viral traffic in social features. - Integration with CloudFront?
Answer: For edge caching and distribution. Real-World Example: Accelerated static/media APIs. - Import/export APIs?
Answer: Via OpenAPI specs. Real-World Example: Migrate legacy gateways. - WebSocket connection management?
Answer: Routes for connect/disconnect; state in DynamoDB. Real-World Example: Collaborative editing sessions. - Security policies for REST APIs (2025)?
Answer: Enhanced TLS with PQC options. Real-World Example: FIPS for regulated workloads. - Integration with Step Functions?
Answer: Synchronous executions via proxy. Real-World Example: Long-running API orchestrations. - With ECS/EC2 backends?
Answer: Via VPC Links; 2025 ALB private. Real-World Example: Hybrid monolith proxies. - Free tier details?
Answer: 1M requests/month for REST/HTTP. Real-World Example: MVP prototyping. - API versioning best practices?
Answer: Path or header-based with stage management. Real-World Example: Graceful deprecation. - Integration with Amazon Q or AI tools (2025)?
Answer: Via Bedrock MCP for assisted design. Real-World Example: Auto-tool generation. - Routing rules in APIs (recent updates)?
Answer: Advanced header/path-based routing. Real-World Example: Dynamic marketing redirects. - Debugging issues?
Answer: Execution logs, X-Ray traces. Real-World Example: Resolve errors in production. - IP address support?
Answer: Dual-stack IPv4/IPv6. Real-World Example: Modern IoT compatibility. - What’s new in API Gateway for 2025?
Answer: Developer Portals, MCP proxy, ALB private integration, response streaming, enhanced TLS (including PQC). Real-World Example: AI-agent enabled developer ecosystems. - Cost optimization tips?
Answer: Prefer HTTP APIs, enable caching, monitor usage. Real-World Example: Cut costs significantly with caching in read-heavy apps. - S3 integrations?
Answer: Proxy for static hosting or presigned operations. Real-World Example: Secure asset delivery.
Tips for AWS API Gateway Interviews in 2025
- Practice Hands-On: Deploy a REST API with Lambda, Cognito, and explore new portals/streaming in free tier.
- Certifications: AWS Developer or Solutions Architect covers API Gateway extensively.
- Focus Areas: 2025 features like MCP for AI, streaming, and security enhancements.
- Stay Updated: Monitor AWS re:Invent announcements for Bedrock integrations.
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Conclusion
Mastering AWS API Gateway in 2025 means leveraging its latest innovations for secure, scalable, AI-integrated APIs. These questions and answers will prepare you thoroughly—combine with labs for best results. Explore more at www.clouddevopsjobs.com.
