System Design & API Design Patterns: Study Guide for 79 Flashcards

System design interviews reward one skill above all: naming the right building block for a constraint, fast. The Flip It deck System Design & API Design Patterns (code UE0645, 79 cards) is built for exactly that. Here is how to get through it efficiently, and which cards to tidy up first.

Two decks in one

Cards 1-50 cover distributed systems: scaling, storage, consistency and resilience. Cards 51-79 switch to API design: REST, HTTP, auth and gateway patterns. Study them as two separate blocks rather than one long shuffle. The architecture block is about trade-offs; the API block is about precise facts (status codes, headers, methods), and mixing them blurs both.

Cards worth knowing cold

What the deck covers

Vertical vs horizontal scaling, load balancing, replication (primary-secondary), CDN, caching, stateless vs stateful servers, message queues, publish-subscribe, SPOF, SLA, CAP theorem, eventual vs strong consistency, ACID vs BASE, denormalization, SQL vs NoSQL, reverse proxy, georouting, indexing, connection pooling, webhooks, idempotency, Raft and Paxos, Byzantine fault tolerance, two-phase commit, Bloom filters, heartbeats, back pressure, strangler fig, bulkhead, REST constraints, CRUD-to-HTTP mapping, 2xx/4xx/5xx codes, API versioning, cursor pagination, OAuth 2.0, JWT, HATEOAS, API Gateway, GraphQL, the repository pattern, token bucket and leaky bucket throttling, content negotiation, CORS, Cache-Control and ETag, and OpenAPI.

Fixes before you start

• Merge the duplicates across the two blocks. Rate limiting appears three times (cards 18, 62, 71), and webhooks (32/72), idempotency (33/55), sync vs async (31/78) and eventual consistency (21/48) each appear twice. Keep the version with more detail, which is usually the one in the API block, since it names concrete techniques like the token bucket.
• Sharpen the CAP card (20). It says a system guarantees any two of three. In practice, network partitions are not optional, so the real choice is consistency vs availability during a partition. Add PACELC on the back: when there is no partition, you trade latency for consistency.
• Drop or move card 2. It lists UI, data and process design as the main components of system design, which is textbook software engineering, not what an interviewer means. Card 50 (ML system design) is also a stray; give it its own tag.

A tip that works for this topic

Turn every pattern card into a trigger card. On the back of Circuit breaker, Bulkhead, Saga and Back pressure, add one line saying which failure each one answers: a slow dependency, resource exhaustion, a cross-service transaction, an overwhelmed consumer. Interview questions describe the symptom, never the pattern's name, so reviewing symptom-to-pattern is what transfers.

Keep going

The API block overlaps with our guide to REST, GraphQL and HTTP status codes. For the algorithms side of interviews, see sorting, searching and graph algorithms.

Find deck UE0645 in the library on Flip It.