System Design Primer: Learn large-scale architecture through system design topics and interview questions
An architecture guide for engineers preparing for system design interviews, using CAP, caching, and real cases to explain large-scale trade-offs.
GitHub donnemartin/system-design-primer Updated 2026-09-04 Branch master Stars 367.5K Forks 58.2K
Python Shell System design Large-scale systems CAP theorem System design interviews

🧭 Decision Guide

Try it if you

  • You are preparing for a system design interview and need to review topics from CAP theorem and databases to caching.
    The README section “Index of system design topics” lists CAP theorem, Database, and Cache.
  • You want to practice open-ended architecture questions using Pastebin, Twitter, or a web crawler.
    The README section “System design interview questions with solutions” lists these questions and paths under solutions.
  • You need to discuss a system that scales to millions of users on AWS.
    The README question table includes “Design a system that scales to millions of users on AWS”.

Skip it if you

  • You are looking for a Python or Shell runtime component that can be integrated directly into a production system.
    The core description is “Learn how to design large-scale systems” and “Prep for the system design interview”; the README material presents topics, questions, and documentation.
  • You need a project with an established version number and release package.
    Project metadata shows 0 releases and the latest version as “No releases”.
  • You must confirm explicit open-source license terms before adopting the material.
    The project license is listed as “Other” in metadata, and the material provides no specific terms.

Requirements

  • The README does not provide installation commands or Python and Shell version requirements.
  • The README section “System design topics: start here” only states that learners need a basic understanding of common principles.

Watch out

  • The object-oriented design content should not be treated as a complete module because the README explicitly marks it as under development.
    The README section “Object-oriented design interview questions with solutions” says “Note: This section is under development”.
  • Some content consists of summaries and trade-off descriptions, so deeper material requires following each section's links.
    The README “Index of system design topics” says each section contains summaries, pros and cons, and links to more in-depth resources.
  • You cannot select a specific release version from the project metadata because there are currently no releases.
    Development activity data shows 0 releases and the latest version as “No releases”.

Alternatives

  • Company engineering blogs:This is more suitable when you need specific company architecture practices instead of the README's topic summaries and interview questions.
    README section “Company engineering blogs”
  • Real world architectures:This is more suitable when you want to study real system architecture cases instead of primarily practicing Pastebin or Twitter interview questions.
    README section “Real world architectures”

Not stated in the README

  • The README material does not specify minimum Python or Shell versions.
  • The README material does not provide installation, build, or automation commands.
  • The README material does not specify the file format, import steps, or maintenance scope of the Anki flashcards.
  • The README material does not state whether the system design cases have performance tests or production validation.
  • The license is listed as Other, but the material does not provide the exact license name or redistribution conditions.
  • The material does not explain the specific maintenance responsibilities associated with 10 contributors and 10 recent commits.
  • The material does not explain the direct reason for the relationship between GitHub Trending and the project's current attention.
  • The material does not provide enough evidence to determine why the project is currently trending.

💡 Deep Analysis

7
No I review production-platform architectures and currently care about high availability, replication, sharding, caching, and message queues. I must also cover monitoring and alerting, disaster-recovery exercises, data migration, access governance, cost, and compliance. Can this project serve as the primary basis for production design?
For: A platform engineer who wants to use system-design material in production architecture reviews and cares about high availability, observability, disaster recovery, migrations, and compliance

No, because the project is a learning and interview-preparation resource, not a production architecture template, cloud framework, or deployable codebase.

  • The README motivation is limited to “Learn how to design large-scale systems” and “Prep for the system design interview,” indicating an educational and interview focus rather than production delivery.
  • Project insights explicitly state that the cases have teaching and interview abstractions and generally do not fully cover monitoring, alerting, disaster-recovery exercises, data migration, access governance, compliance, cost control, or concrete cloud-service configuration. Those are exactly the areas you require.
  • Although the README covers availability, replication, sharding, caching, message queues, and security, these topics are organized mainly around concepts, pros and cons, and trade-offs—not complete runbooks or validated deployment designs.
  • Project data shows release_count is 0 and latest_release is empty; the license field is “Other.” That does not support treating the repository as a dependency with a stable release or compatibility promise.

It can support conceptual review before an architecture discussion, but it cannot independently justify production decisions. The README does not specify SLOs, monitoring implementations, disaster-recovery RPO/RTO, migration procedures, or compliance controls.

  • README section “Motivation” and quotes “Learn how to design large-scale systems.” and “Prep for the system design interview.”
  • README topic index entries “Availability patterns,” “Replication,” “Sharding,” “Cache,” “Asynchronism,” and “Security”
  • Project insights: the cases generally do not fully cover monitoring, alerting, disaster recovery, migration, compliance, cost, or concrete cloud-service configuration
  • Project data: release_count is 0; latest_release is empty; license is “Other”
Not stated in the README:The README does not specify a production environment, cloud-provider versions, SLO/RPO/RTO targets, or security and compliance standards;It does not define the licensing boundaries for internal enterprise use, training, or redistribution of third-party references and derivative material
Yes I am preparing for a system design interview and focusing on problems such as the Twitter timeline, a web crawler, and an AWS system that scales to millions of users. I need material covering requirements, architecture, scaling, and capacity estimation. Is this project suitable for me?
For: A software engineer preparing for a mid-to-senior backend or distributed-systems interview who needs to practice the full flow from requirements clarification to capacity estimation

Yes, it is suitable because it is organized specifically around large-scale system-design interviews rather than merely listing infrastructure components.

  • “How to approach a system design interview question” describes the interview as an open-ended conversation and presents steps for clarifying use cases, constraints, and assumptions; creating a high-level design; designing core components; scaling the design; and performing back-of-the-envelope calculations.
  • “System design interview questions with solutions” includes the Twitter timeline and search, a web crawler, Pastebin, Mint, and “Design a system that scales to millions of users on AWS,” which directly matches your target practice set.
  • The topic index covers latency versus throughput, availability versus consistency, replication, sharding, caching, message queues, TCP/UDP, RPC, REST, and security, allowing you to connect case studies back to reusable concepts.

It is better viewed as an interview reasoning framework and reference collection than as an executable AWS deployment guide. The README does not specify whether each exercise includes complete monitoring, disaster recovery, cost modeling, or concrete AWS configuration.

  • README section “How to approach a system design interview question”
  • README section “System design interview questions with solutions”
  • README quote: “Everything is a trade-off.”
  • README cases: “Design the Twitter timeline and search,” “Design a web crawler,” and “Design a system that scales to millions of users on AWS”
Not stated in the README:The supplied README excerpt does not state the depth of each solution, expected practice time, or whether runnable AWS labs are provided;It does not state whether the solutions cover current AWS services or the evaluation criteria of specific interview companies
Yes I am reviewing CAP, master-slave and master-master replication, sharding, SQL versus NoSQL, cache-update strategies, and message queues, and I want to use the project's Anki flashcards for review. Can it support a systematic review plan?
For: A distributed-systems learner who needs to review database, caching, and asynchronous-architecture trade-offs and reinforce concepts with Anki flashcards

Yes, it is particularly suitable for placing distributed-systems concepts into one review structure and reinforcing them with Anki.

  • The README topic index organizes material around performance and scalability, latency and throughput, availability and consistency, CAP, replication, databases, caching, asynchronism, and communication.
  • The database section distinguishes RDBMS, master-slave replication, master-master replication, federation, sharding, denormalization, SQL tuning, and key-value, document, wide-column, and graph databases.
  • The cache section covers client, CDN, web-server, database, and application caching, as well as cache-aside, write-through, write-behind, and refresh-ahead. The asynchronism section covers message queues, task queues, and back pressure.
  • The README provides an “Anki flashcards” entry, and the project description explicitly says “Includes Anki flashcards.”

Because the project emphasizes that “Everything is a trade-off,” it is best for reviewing definitions, applicability, and pros and cons—not for learning the implementation of a particular database or messaging system. The README does not specify the flashcard count, update frequency, or language coverage.

  • README quote: “Summaries of various system design topics, including pros and cons. Everything is a trade-off.”
  • README section “Database” and its RDBMS, NoSQL, and Sharding subsections
  • README section “Cache” and the “Cache-aside,” “Write-through,” “Write-behind,” and “Refresh-ahead” subsections
  • README section “Asynchronism”; project description: “Includes Anki flashcards”
Not stated in the README:The README does not specify the exact card count, card schema, maintenance status, or consistency across language versions;It does not state whether each database, cache, or messaging topic has an executable lab
It depends I am a computer-science student who wants to start with scalability, performance, latency, and throughput, then practice Pastebin, social-network data structures, and a search-engine key-value store. If I am not yet comfortable with TCP, databases, or caching, is this project suitable as my primary textbook?
For: A computer-science student who wants to progress from system-design fundamentals to classic Internet architecture problems but has not yet built a foundation in networking, databases, and backend development

It depends: it works well as a structured entry point, but it should not be your only primary textbook for building networking, database, and distributed-systems fundamentals from scratch.

  • “System design topics: start here” tells new learners to first understand common principles, how they are used, and their pros and cons, beginning with a scalability video lecture and article.
  • The index then moves across TCP, UDP, databases, caching, message queues, and security. This provides broad coverage, but it also requires switching among several foundational areas.
  • The case-study section includes Pastebin, social-network data structures, and a key-value store for a search engine, connecting abstract concepts to concrete design exercises.
  • Project insights rate the learning curve as moderate and state that understanding CAP, replication, sharding, cache invalidation, and capacity estimation requires networking, database, operating-system, and backend knowledge. The README is approximately 109,682 in length and highly dense.

Use it as a learning map and case index. If you lack the prerequisites, pair it with introductory networking, database, and operating-system material. The README does not define a complete zero-to-beginner curriculum or prerequisite checklist.

  • README section “System design topics: start here”
  • README quote: “New to system design? First, you'll need a basic understanding of common principles...”
  • README cases: “Design Pastebin.com (or Bit.ly),” “Design the data structures for a social network,” and “Design a key-value store for a search engine”
  • Project insights: moderate entry difficulty; README length is approximately 109,682
Not stated in the README:The supplied README excerpt does not provide a complete beginner curriculum organized by week or chapter;It does not specify the versions or availability of the referenced videos, articles, and external resources
Yes I prefer Simplified Chinese but need to consult the English material for CAP, RPC, caching, and AWS cases. I want to navigate through indexes, anchors, and translation links rather than follow one linear tutorial. Is the user experience suitable for me?
For: A self-directed developer who wants to switch between English material and the Simplified Chinese entry point while navigating system-design topics through indexes and anchors

Yes, provided that you are comfortable using it as a dense, topic-oriented repository rather than as one linear course.

  • The top of the README links to English, Simplified Chinese, Traditional Chinese, Japanese, and other language entries, and includes “Add Translation” and “Help translate this guide!” links, making language switching practical.
  • “Index of system design topics” organizes CAP, RPC, REST, databases, caching, message queues, and security through many section anchors, which supports targeted lookup.
  • Project insights describe the README as approximately 109,682 characters with dense chapter links. It is suited to navigation through the table of contents, anchors, and repository files rather than a single linear reading path.
  • However, the available language versions may not have identical update status or coverage, and the information density is high. If you expect every chapter to have synchronized translation and a continuous lesson sequence, the experience may be inconsistent.

The README does not specify synchronization rules, update timing, or complete coverage percentages for each language version.

  • README language links at the top: English, Simplified Chinese, Traditional Chinese, Japanese, and others
  • README top-level text: “Help translate this guide!” and the “Add Translation” link
  • README section “Index of system design topics”
  • Project insights: README length is approximately 109,682, with dense chapter links and topic-oriented navigation
Not stated in the README:The README does not specify synchronization timing or missing content between the Simplified Chinese and English versions;It does not state whether the translation process provides centralized review, version markers, or coverage statistics
It depends I mainly write Python and want to practice object-oriented design problems such as hash tables, LRU caches, call centers, and parking lots. I also want notebooks or code implementations rather than only reading system-design articles. Is this project suitable for me?
For: A software developer who primarily uses Python and wants to practice hash tables and LRU caches through object-oriented design problems and notebooks

It depends: the project is suitable for focused Python and object-oriented exercises, but not as a complete, unified Python engineering-training framework.

  • The README section “Object-oriented design interview questions with solutions” includes hash tables, LRU caches, call centers, cards, parking lots, chat servers, and circular arrays, matching your requested practice areas.
  • Project insights state that some object-oriented design material is provided as Python notebooks or code examples. The project data reports 57,260 lines of Python, so the repository is not purely textual.
  • However, the insights also state that the code does not form one deployable system, and that the repository has no unified execution entry point or complete test suite. The README also contains an “Under development” section, indicating uneven completion.

Use it to understand design ideas and modify individual implementations. Do not treat it as a ready-to-reuse, production-tested Python data-structure library, because the supplied evidence does not support that conclusion.

  • README section “Object-oriented design interview questions with solutions”
  • README section “Under development”
  • Project data: main_language is Python; Python code size is 57,260
  • Project insights: some object-oriented design material is provided as Python notebooks or code examples; there is no unified entry point or complete test system
Not stated in the README:The supplied excerpt does not list the Python version, dependency installation method, or test coverage for each notebook;It does not identify which implementations are complete and which remain under development
It depends I am preparing for platform-engineering and backend interviews. I need to practice availability, load balancing, database sharding, and message queues, while also solving object-oriented problems such as LRU caches, hash tables, and chat servers. I also want to use the Interactive Coding Challenges. Can this repository cover both preparation tracks?
For: A Python developer preparing for platform-engineering and backend interviews who needs both system-design and object-oriented-design practice, supplemented by interactive coding challenges

It depends: the repository places both preparation tracks in one place, but the depth and continuity of the system-design material and coding challenges are not necessarily equivalent.

  • The system-design index covers availability patterns, fail-over, active-active and active-passive designs, load balancers, horizontal scaling, database sharding, caching, and message queues, which fits architecture discussions for platform and backend interviews.
  • The object-oriented design solutions include hash tables, LRU caches, chat servers, call centers, parking lots, and circular arrays, providing a second interview-practice track.
  • The README also includes “Coding Resource: Interactive Coding Challenges” and “Anki flashcards,” indicating additional routes for coding practice and memory review.
  • However, project insights report 57,260 lines of Python and only 1,192 lines of Shell; the code does not form a unified deployable system and there is no complete test suite. Therefore, you should not assume that every topic has an equally extensive runnable problem set.

For unified reference and interview practice, it can cover both areas. For a continuous algorithms course, a full evaluation platform, or production-grade implementations, it is not a complete solution. The README does not specify the challenge count, evaluation mechanism, or completion status.

  • README topic-index entries “Availability patterns,” “Load balancer,” “Horizontal scaling,” “Sharding,” “Cache,” and “Message queues”
  • README section “Object-oriented design interview questions with solutions”
  • README sections “Coding Resource: Interactive Coding Challenges” and “Anki flashcards”
  • Project data: 57,260 lines of Python and 1,192 lines of Shell
  • Project insights: the code does not form a unified deployable system and there is no complete test suite
Not stated in the README:The supplied README excerpt does not state whether interactive challenges run inside the repository, require an external platform, or support automated judging;It does not state the number, maintenance status, or difficulty levels of the object-oriented and system-design exercises

✨ Highlights

  • Covers CAP, caching, sharding, and NoSQL system design topics
  • Provides Pastebin, Twitter, and web crawler case studies
  • Includes an AWS millions-of-users scaling design question and solution
  • Has 367,820 stars and 58,221 forks

🔧 Engineering

  • Explains CAP, load balancers, databases, caches, and message queues by topic
  • Pairs Pastebin, Twitter, and web crawler questions with solutions examples
  • Provides object-oriented design questions such as hash maps and LRU cache

⚠️ Risks

  • The README marks the object-oriented design section as under development
  • The project has no version releases; metadata shows No releases
  • The license is listed as Other, with no specific terms provided in the material

👥 For who?

  • Engineers preparing for system design interviews and reviewing CAP and scalability
  • Developers comparing trade-offs among RDBMS, NoSQL, and caching strategies
  • Learners practicing architecture discussions with Twitter and Mint.com cases