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Backend Developer Interview Guide: Concepts, Scenarios & System Design
Use this backend developer interview guide to prepare APIs, databases, caching, distributed systems, production scenarios, and system design.
22 min read
Structured learning path
Backend Interview Mastery
Follow this series from the first concept to the final deep dive. Every article is arranged in the recommended reading order.
Start with article 1- Articles
- 32
- Study time
- 605 min
Your path
Read in order
32 focused lessons
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- Read 2
Client-Server Architecture Explained for Backend Interviews
Learn client-server architecture for backend interviews: request flow, tiers, state, scaling trade-offs, and production failure points.
14 min read - Read 3
What Is a REST API? Principles, Examples and Interview Questions
What is a REST API? Learn resource design, HTTP semantics, idempotency, and the interview answers backend engineers need.
19 min read - Read 4
HTTP Methods: GET vs POST vs PUT vs PATCH vs DELETE
Master HTTP methods for backend interviews: GET, POST, PUT, PATCH, and DELETE semantics, retries, caching, and API design trade-offs.
23 min read - Read 5
HTTP Status Codes Explained: 200, 404, 500 and More
Master HTTP status codes for backend interviews: 200, 201, 400, 401, 403, 404, 409, 429, 500, and 503 with API examples.
25 min read - Read 6
Stateless vs Stateful Architecture for Backend Interviews
Learn stateless vs stateful architecture for backend interviews: where state lives, scaling trade-offs, sessions, Redis, and failure recovery.
11 min read - Read 7
Authentication vs Authorization: Backend Interview Guide
Master authentication vs authorization for backend interviews, including 401 vs 403, sessions, JWTs, API checks, and permission models.
22 min read - Read 8
How JWT Works: Header, Payload, Signature and Security
Learn how JWT works for backend interviews: header, payload, signature, expiry, validation, key rotation, and API security pitfalls.
20 min read - Read 9
API Gateway Explained: Architecture, Responsibilities and Trade-offs
Learn API gateway architecture for backend interviews: routing, authentication, rate limiting, aggregation, failure handling, and trade-offs.
10 min read - Read 10
API Rate Limiting: Fixed Window, Sliding Window and Token Bucket
Learn API rate limiting for backend interviews: fixed and sliding windows, token bucket, Redis atomicity, 429 responses, and trade-offs.
9 min read - Read 11
Idempotency in REST APIs: How to Prevent Duplicate Payments
Learn idempotency in REST APIs for backend interviews: idempotency keys, retries, race conditions, response replay, and duplicate-payment prevention.
15 min read - Read 12
Offset vs Cursor vs Keyset Pagination for Backend Interviews
Compare offset, cursor, and keyset pagination for backend interviews: performance, consistency, indexes, API contracts, and trade-offs.
12 min read - Read 13
Webhooks Explained: Delivery, Retries, Security and Idempotency
Learn webhooks for backend interviews: delivery flow, retries, HMAC signatures, replay protection, idempotency, queues, and failure handling.
15 min read - Read 14
What Is CORS? Backend Guide to Preflight and Security
Learn what CORS is for backend interviews: browser origins, preflight requests, credential rules, safe headers, and production debugging.
21 min read - Read 15
API Gateway vs Load Balancer vs Reverse Proxy
Compare API gateways, load balancers, and reverse proxies for backend interviews: responsibilities, request flow, overlap, and architecture trade-offs.
13 min read - Read 16
SQL vs NoSQL: How to Choose in System Design
Compare SQL vs NoSQL for system design: data modeling, transactions, scale, trade-offs, and the right database for each workload.
21 min read - Read 17
Database Indexing Explained: SQL Examples and Interview Questions
Learn database indexing with SQL examples: B-tree indexes, query plans, composite index order, write costs, and interview questions.
20 min read - Read 18
Composite Index Column Order: How to Choose the Right SQL Index
Learn how to choose composite index column order for SQL queries using equality, range, sort, selectivity, and EXPLAIN plan trade-offs.
24 min read - Read 19
Database Isolation Levels Explained With Real Transaction Examples
Learn database isolation levels through real transaction examples, including dirty reads, phantoms, write skew, retries, and SQL trade-offs.
16 min read - Read 20
Optimistic vs Pessimistic Locking: How to Choose
Compare optimistic vs pessimistic locking with SQL examples, conflict handling, retries, deadlocks, and practical backend trade-offs.
12 min read - Read 21
Database Deadlocks: Causes, Detection, and Prevention
Learn database deadlocks through transaction examples, wait-for cycles, retries, lock ordering, query design, and production prevention practices.
12 min read - Read 22
Database Replication: Read Replicas, Lag, and Failover
Learn database replication, read replicas, replication lag, stale reads, and failover trade-offs for reliable backend systems.
25 min read - Read 23
Why Is My SQL Query Slow? A Backend Debugging Guide
Learn why SQL queries are slow and use EXPLAIN ANALYZE, query plans, indexes, and production evidence to fix them safely.
20 min read - Read 24
Cache-Aside Pattern: Read and Write Flows Explained
Learn the cache-aside pattern, cache hit and miss flows, write invalidation, TTLs, stampede prevention, and production trade-offs.
19 min read - Read 25
Write-Through vs Write-Back Caching: Key Differences
Compare write-through vs write-back caching: write latency, durability, consistency, failure recovery, and when each cache write strategy fits.
21 min read - Read 26
Cache Eviction Policies: LRU, LFU, FIFO and TTL
Learn cache eviction policies including LRU, LFU, FIFO, and TTL. Choose a policy using workload patterns, memory limits, and production metrics.
23 min read - Read 27
Redis Architecture: Data Types, Persistence and Scaling
Learn Redis architecture through data types, persistence, replication, failover, clustering, and the production trade-offs behind fast in-memory systems.
19 min read - Read 28
Cache Invalidation Strategies: TTL, Events and Versioned Keys
Learn cache invalidation strategies for backend systems: TTLs, delete-on-write, event-driven updates, versioned keys, race conditions, and trade-offs.
27 min read - Read 29
Cache Stampede: Avalanche, Penetration and Prevention
Learn cache stampede prevention for avalanche and penetration failures with TTL jitter, request coalescing, stale data, and Bloom filters.
29 min read - Read 30
Queue vs Pub/Sub: When to Use Each Pattern
Compare queue vs pub/sub patterns for backend systems. Learn delivery models, retries, fanout, ordering, and how to choose the right fit.
20 min read - Read 31
Kafka Architecture: Producers, Brokers, Topics and Offsets
Learn Kafka architecture through producers, brokers, topics, partitions, consumers, and offsets. Understand ordering, replication, lag, and trade-offs.
22 min read - Read 32
Kafka Partitions: Ordering, Keys and Parallelism Explained
Learn Kafka partitions, message keys, ordering, and consumer parallelism with production trade-offs, sizing guidance, and interview questions.
24 min read