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Backend Fundamentals

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Start here. A hand-picked path through the core ideas every backend engineer needs — how large systems scale, how databases stay fast, and how programs do many things at once. Free to start, designed to give you a real win.

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Start: System Design Basics →

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  1. 1

    System Design Basics

    Learn the fundamental principles behind building large-scale, reliable systems: scalability, availability, latency, and the key trade-offs that drive real-world architecture decisions.

    Free Start →
  2. 2

    Database Indexing

    Learn how B-tree and hash indexes work internally, how the query planner uses them, when to create composite and covering indexes, and how to diagnose slow queries using EXPLAIN ANALYZE.

    Pro Start →
  3. 3

    Concurrency vs Parallelism

    Untangle four words engineers constantly confuse: concurrency, parallelism, threads, and processes. Learn what runs truly simultaneously versus what merely interleaves, why Python's async model is single-threaded, and how getting this wrong causes real production bugs like sharing one database session across coroutines.

    Free Start →