APIs, Networking & Integration Topics
API design, management, and integration patterns including REST, GraphQL, and other protocols. Covers API contract design, versioning strategies, error handling, idempotency, deprecation planning, and SDK/integration frameworks. Includes system-to-system integration, webhook patterns, and integration platform considerations. Excludes network infrastructure and network-layer protocols (see Network Architecture under Cloud & Infrastructure or a dedicated networking category if needed).
RESTful API Design and HTTP Fundamentals
Understanding REST architectural principles including resource-based URLs, proper HTTP methods (GET for safe retrieval, POST for creation, PUT for updates, DELETE for deletion), appropriate status codes (200 OK, 201 Created, 400 Bad Request, 404 Not Found, 500 Internal Server Error), and stateless communication patterns. Ability to design simple API endpoints following REST conventions.
Application Programming Interface Design and Integration
Designing Application Programming Interfaces and selecting communication protocols to meet functional and non functional requirements. Candidates should be able to evaluate and choose between Representational State Transfer style resource oriented interfaces, Graph Query Language approaches, remote procedure call frameworks such as Google Remote Procedure Call, and message based or event driven integration patterns. Discussion should cover protocol and format trade offs including latency, throughput, consistency and ordering, binary versus text serialization formats such as protocol buffers or JavaScript Object Notation, developer ergonomics, client diversity, and resource consumption. Core design topics include contract design and schema evolution, versioning and backward compatibility strategies, pagination, filtering, sorting and error handling conventions, authentication and authorization models, rate limiting and quota strategies, caching choices, and gateway or proxy patterns. Integration concerns include direct synchronous calls, asynchronous message based decoupling, event streaming, and web hooks, plus client and server software development kits and data transformation between layers. Candidates should also explain resilience and reliability patterns such as timeouts, retries, circuit breaker and bulkhead techniques, and describe testing, monitoring and observability approaches including logging, metrics and distributed tracing. Finally, discussion should connect API and protocol choices to coupling, scalability, operational complexity, security posture, and developer productivity.
Data Management and API Design
Designing how applications structure, expose, and consume data through APIs and backend systems. Covers API design principles for data endpoints, pagination, filtering and sorting, idempotency, versioning, rate limiting, schema design, normalization versus denormalization, consistency models, caching strategies, client side fetching patterns, and error handling. Includes considerations for data integrity across integrations, transactional boundaries, master data management, and how API decisions affect downstream consumers and performance.
Application Programming Interface Design and Scalability
Designing application programming interfaces that remain reliable, performant, and maintainable at high scale. Candidates should understand how interface decisions affect scalability, availability, latency, and operational complexity and be able to reason about trade offs between client complexity and server responsibility. Core areas include stateless interface design, pagination and cursor strategies for large result sets, filtering and search optimization, payload minimization, batching and streaming, and techniques to reduce server load while preserving client experience. Resilience and operational controls include rate limiting and quota management, throttling, backpressure and flow control, retry semantics and idempotency patterns, error format design and explicit identification of retryable errors, and strategies for graceful degradation under overload. Evolution and compatibility topics include backward compatible versioning strategies, deprecation policies, contract design and testing approaches to avoid breaking consumers. Infrastructure and deployment considerations include API gateway and edge patterns, interaction with load balancers and traffic distribution, caching and content delivery, routing fault tolerance, health checks and canary rollout strategies, and observability through metrics, distributed tracing, and logging to support capacity planning and incident response. Security considerations such as scalable authentication and authorization, credential and key management, and permission models are also important. Candidates should be prepared to discuss concrete patterns, trade offs, algorithms, and operational playbooks for designing and running high traffic application programming interfaces.
Integration Patterns and API Design
Focuses on integration concepts, data flow, and API design as the foundation for connecting systems and services. Coverage includes data integration techniques such as ETL and ELT, change data capture, data warehousing, synchronization and eventual consistency challenges, latency and throughput considerations, middleware and messaging solutions, and common integration patterns used in marketing and enterprise stacks. For APIs, topics include what APIs are and why they matter for developer products, REST versus GraphQL trade offs and use cases, HTTP methods and semantics, authentication and authorization patterns, rate limiting and throttling, versioning strategies, idempotency and error handling, documentation and developer experience, monitoring and service level considerations, and how API choices affect product and business decisions.
Application Programming Interface Design and Strategy
Covers the design, developer experience, and strategic operating decisions for Application Programming Interfaces and developer platforms. Candidates should demonstrate core design principles such as simplicity, consistency, discoverability, clear naming and conventions, intuitive resource modeling, robust error handling, stability, backward compatibility, and explicit versioning strategies. They should understand trade offs among interface paradigms including Representational State Transfer style APIs, Graph Query Language approaches, and remote procedure call frameworks such as gRPC, and how those choices affect discoverability, latency, schema evolution, client ergonomics, testing, and mocking. The topic also includes the developer facing surface area beyond the interface itself: documentation, quickstart guides, sample code, software development kits, command line tools, interactive explorers, sandbox environments, and other onboarding artifacts that reduce friction. Candidates should be able to identify common friction points such as unclear documentation, complex setup and authentication flows, unhelpful error messages, inconsistent or surprising behaviors, slow feedback loops, and endpoints that are hard to mock or test, and propose concrete engineering and process solutions. Measurement and optimization expectations include onboarding and adoption metrics such as time to first successful call, time to first meaningful result, onboarding success rates, developer satisfaction and sentiment, adoption and churn, support and integration costs, error rates and latency, and how to instrument and monitor the developer journey. Engineering practices to discuss include stable contract design, semantic versioning and compatibility guarantees, schema and contract testing, clear deprecation policies, monitoring and observability for developer journeys, automated client generation and migration tooling, authentication and rate limiting strategies, webhook and event mechanisms, and monetization or partnership models for platform growth. Senior candidates should connect technical and experience decisions to product and business outcomes, explaining how design choices drive adoption, reduce support load, enable ecosystem growth, and preserve long term platform velocity, and should provide concrete examples of improvements implemented or proposed and how their impact was measured.
Migrations, Versioning & Compatibility at Scale
Understand how to design systems that support long-term evolution while maintaining compatibility. Discuss strategies for API versioning, gradual deprecation of old versions, and migration paths for customers. Be able to discuss how to maintain backward compatibility while evolving a system, and trade-offs between maintaining multiple versions versus forcing migrations. For large platforms, discuss how to coordinate migrations across thousands of dependent systems.
API and Interface Design
Design clear and composable Application Programming Interfaces and public interfaces for services and libraries. Cover specifying inputs, outputs, error signaling, versioning, backward compatibility, authentication and authorization, rate limiting and throttling, pagination and filtering, and schema design. Emphasize idempotency, client ergonomics, documentation and contract testing, monitoring and observability hooks, and when to avoid premature optimization or over engineering.
Client Heterogeneity and Compatibility
Design and operational strategies for supporting a heterogeneous population of clients, such as mobile apps, web frontends, desktop applications, IoT devices, and third-party API consumers, that run different versions and support different capabilities at scale. Topics include API versioning and backward compatibility, runtime capability detection and graceful degradation, feature flagging and progressive rollout mechanisms, staged migration and sunset strategies for deprecated client versions, packaging and resource strategies for different client environments and hardware profiles, testing approaches including compatibility test matrices and targeted beta or canary programs, and telemetry driven detection and mitigation of compatibility regressions. Candidates should discuss trade offs between minimizing fragmentation and advancing the platform or API while preserving experience for all supported client types.