SysDesignPrep.com

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System Design Primer alternative: SysDesignPrep.com vs System Design Primer

A free, open-source guide on GitHub: the core topics with links to further reading, eight system design questions with solutions, and Anki flashcards.

The System Design Primer is one of the most popular free resources on system design, and deserves to be. It walks through the core topics (performance and scalability, latency and throughput, CAP, caching, replication, sharding, load balancing, queues), links to deeper reading on each, solves eight classic questions (Pastebin, the Twitter timeline, a web crawler, a key-value store for a search engine and others), and comes with Anki decks for spaced repetition.

It is a reference to read, and it costs nothing. SysDesignPrep.com is where you practise saying it: a strong candidate’s interview you step through turn by turn, with the design drawn as they talk, then an AI interviewer that asks follow-ups on your own answer.

System Design PrimerSysDesignPrep.com
FormatOne long guide of topics with links, plus solved questions and flashcardsInteractive interview walkthroughs, then AI mock interviews, with reference designs, study guides and interactive concepts
Questions with solutionsEight system design and six object-oriented design questions83 system design questions, each with a walkthrough, a reference design and deep dives
PracticeReading and Anki flashcardsYou answer at each decision, then sit the question with an AI interviewer and get a scored debrief
Asking “why?”Follow the links to the source articlesThe AI Mentor beside the interview, in context
PriceFree and open sourceReference designs and study guides free; walkthroughs free with a Google sign-in; Pro $49 a month for the AI interviewer and Mentor

Choose System Design Primer if

  • You want a free, compact map of the topics and where to read more.
  • You learn well with flashcards and spaced repetition.

Choose SysDesignPrep.com if

  • You know the topics and need to rehearse a full 45-minute answer out loud.
  • You want more worked questions, each with the follow-ups an interviewer asks after your first answer.
  • You want to start free: every reference design and study guide is open.

Many people use both: the Primer to map the topics, then the questions here to practise putting them together under time. The fastest way to see the difference is the free walkthrough, which needs no sign-up.

Try the free walkthroughSee all 83 questions

What we say about System Design Primer is from its own site, checked in October 2026: github.com/donnemartin/system-design-primer. Products change; if something here is out of date, tell us and we will fix it.

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