Design Fundamentals

System Design Interview Wiki

Master the blueprints of planet-scale infrastructure. From distributed consensus to eventual consistency, learn the architectural patterns that distinguish Staff Engineers and develop the intuition to navigate complex trade-offs where there are no right answers—only better choices.

Design

Cassandra

Definition

Apache Cassandra is a highly scalable, high-performance, distributed NoSQL database designed to handle massive amounts of data across many commodity servers, providing high availability with no single point of failure.

Design

WebSocket

Definition

WebSocket is a computer communications protocol providing full-duplex communication channels over a single TCP connection, initiated via an HTTP 'Upgrade' handshake.

Design

Redis

Definition

An open-source, in-memory data structure store used as a database, cache, message broker, and streaming engine, leveraging a single-threaded event loop for extreme performance.

Design

ScyllaDB

Definition

A high-performance, C++ rewrite of Apache Cassandra utilizing a shared-nothing, shard-per-core architecture to maximize modern hardware utilization.

Design

Load Balancing

Definition

A core architectural component that sits between clients and servers, distributing incoming network traffic across a pool of healthy backend resources to optimize resource utilization, maximize throughput, and ensure high availability.

Design

Kafka

Definition

A distributed, partitioned, and replicated commit log service that provides the functionality of a messaging system with a unique design centered around high-throughput, durability, and stream processing.

Design

PostgreSQL

Definition

PostgreSQL is an advanced, open-source Object-Relational Database Management System (ORDBMS) known for its strict adherence to SQL standards, robust ACID compliance, and extreme extensibility.

Design

Elasticsearch

Definition

A distributed, RESTful search and analytics engine built on top of Apache Lucene, designed for horizontal scalability, reliability, and real-time search capabilities.

Design

gRPC

Definition

A high-performance, open-source universal RPC framework that leverages HTTP/2 for transport and Protocol Buffers (Protobuf) as the interface description language and serialization format.

Design

CDN

Definition

A Content Delivery Network (CDN) is a geographically distributed network of proxy servers and data centers (Points of Presence or PoPs) designed to provide high availability and performance by distributing service spatially relative to end-users.

Design

S3

Definition

Amazon S3 is a highly scalable, durable, and performant object storage service designed to store and retrieve any amount of data from anywhere on the web.

Design

SQS

Definition

Amazon Simple Queue Service (SQS) is a fully managed, highly scalable distributed message queuing service designed to decouple and scale microservices, distributed systems, and serverless applications.

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The Definitive Standard

The Foundational Knowledge for Real Interviews.

Every concept explained with the depth, trade-offs, and failure modes that differentiate L5 from L6 engineers at Big Tech.

First-Principles Explanations
Real Interview Trade-offs
Six Technical Domains
Continuously Updated
12+ Concepts

Engineered using the same evaluation criteria employed by senior leadership at Google, Meta, and OpenAI.

20+ Concepts

System Design

Master the blueprints of planet-scale infrastructure. From distributed consensus to eventual consistency, learn the architectural patterns that distinguish Staff Engineers and develop the intuition to navigate complex trade-offs where there are no right answers—only better choices.

Algorithms

Coding Puzzle

Elevate your problem-solving from pattern matching to algorithmic mastery. Build a deep mental library of core data structures and advanced techniques, enabling you to decompose complex problems, optimize with surgical precision, and write clean, industrial-grade code under intense scrutiny.

AI Specialization

ML System Design

Bridge the chasm between research models and production systems. Deconstruct end-to-end architectures for recommendation engines and real-time inference, mastering the critical trade-offs in data freshness, latency, and scalability expected at the world's leading AI labs.

Leadership

Behavioral & Leadership

Command the room with high-stakes leadership narratives. Learn to deconstruct your professional journey through the lens of executive-level competencies—conflict resolution, strategic ownership, and technical influence—to demonstrate the maturity and impact required for senior leadership roles.

Data Mastery

SQL Puzzle

Master the engine behind the data. Go beyond basic queries to understand the mechanics of indexing, query planning, and relational theory, empowering you to design bulletproof schemas and optimize data pipelines that handle massive throughput with uncompromising reliability.

Architecture

Frontend System Design

Architect modern web applications that scale with complexity. Dive into the nuances of state management, rendering strategies, and performance optimization, learning how to build resilient frontend systems that deliver premium user experiences across diverse environments and network conditions.

Your Complete Tech Interview Reference

The Knowledge Hub is designed to be your go-to reference — the kind of resource you bookmark and return to again and again. Whether you're brushing up on Kafka's pub-sub internals, revisiting consistent hashing before a system design round, or looking up dynamic programming patterns for a coding interview, every concept is explained with the depth and precision that top-tier interviews demand.

Each article focuses on the why behind a technology — the trade-offs, real-world failure modes, and interview angles that interviewers at Google, Meta, Amazon, and Apple actually probe. This is not a surface-level overview site. It's a reference engineered for engineers.

What Makes a Great Technical Reference?

The best references are flat, fast, and searchable — not structured into rigid beginner-to-advanced hierarchies. System design, ML systems, and algorithms are sibling disciplines, not a linear ladder. You can tackle Kafka and transformers in the same afternoon. Use the search bar and category filters to navigate exactly where you need to go, when you need it.

Interview-Focused Depth

Interviewers rarely ask “define Kafka.” They ask you to design a notification system and justify your messaging choice. Every article covers the trade-offs and failure modes that separate L5 from L6 candidates.

Six Technical Domains

System Design, Coding Algorithms, ML Design, Frontend Architecture, SQL & Databases, and Behavioral frameworks — all in one place. Filter to focus, or search across everything at once.

First-Principles Thinking

Memorizing answers fails in follow-up questions. Every concept is grounded in first principles — understand CAP theorem not as a definition, but as a real constraint you'd navigate in a production incident.

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