Under the Hood

The Curriculum

Seven tracks, from fetch() down to packets and pages, through to distributed systems and interview craft.

Two deep tracks — networking and databases — go all the way down to packets and pages. The other five stages build back up: the building blocks, the consistency trade-offs, the APIs, the distributed patterns, and the worked case studies an interview actually asks for.

  1. Track NDeep track

    Networking, under the hood

    The full life of a request: from fetch() in your code down to packets, and back.

    12 lessons

  2. Track DDeep track

    Databases, under the hood

    How Postgres actually executes your query: pages, B-trees, WAL, MVCC.

    10 lessons

  3. Track FDeep track

    Frontend, under the hood

    What actually happens inside a UI event or a render: capture/bubble, the rendering pipeline, batching, shared state, and async correctness.

    15 lessons

  4. Track ADeep track

    Animation, under the hood

    What actually happens when something moves on screen: the frame loop, how the browser interpolates, the compositor thread, easing, the Web Animations API, and FLIP.

    8 lessons

  5. Track GDeep track

    GSAP, under the hood

    How the animation library actually works: what a tween is, the single ticker, how it animates anything, timelines as data, its eases and matrix transforms, and ScrollTrigger.

    8 lessons

  6. Track TDeep track

    Three.js & WebGL, under the hood

    How a triangle becomes pixels on the GPU: the rendering pipeline, WebGL as a state machine, geometry and buffers, the model/view/projection matrices, shaders, the scene graph, draw calls, and materials.

    8 lessons

  7. Track WDeep track

    WebAssembly, under the hood

    What that .wasm file really is: a stack-machine bytecode, its flat linear memory, the compile toolchain, the JS boundary, why it is fast, streaming compilation, and WASI beyond the browser.

    8 lessons

  8. Track UDeep track

    WebGPU, under the hood

    The modern GPU API for the web: why it replaces WebGL, the device and queue, explicit buffers, baked render pipelines, WGSL, bind groups, command encoders, and compute shaders.

    8 lessons

  9. Track CDeep track

    Canvas 2D, under the hood

    The immediate-mode drawing surface: why the canvas forgets every shape, the pixel backing store, the drawing state machine, paths, the transform matrix, compositing, text and images, and the performance model.

    8 lessons

  10. Track SDeep track

    Web Audio, under the hood

    Sound as a processing graph on a real-time thread: samples and buffers, source nodes, sample-accurate AudioParam scheduling, gain and mixing, filters and effects, the FFT, and custom DSP with AudioWorklet.

    8 lessons

  11. Track EDeep track

    The event loop, under the hood

    How one thread runs everything: the call stack, the task and microtask queues, where rendering fits, promises and async/await as scheduling, Web Workers, and keeping the loop responsive.

    8 lessons

  12. Track VDeep track

    JavaScript engines, under the hood

    How V8 turns your source into fast machine code: parsing, Ignition bytecode, the TurboFan JIT and deopt, hidden classes and inline caches, value representation, and generational garbage collection.

    8 lessons

  13. Track RDeep track

    The rendering engine, under the hood

    How a page goes from HTML text to pixels: the critical rendering path, DOM and CSSOM construction, selector matching and the cascade, computed style, the render tree, layout, and paint.

    8 lessons

  14. Track KDeep track

    React internals, under the hood

    How React actually works: the virtual DOM and reconciliation, JSX and elements, the diffing heuristics, the fiber tree, render vs commit phases, hooks as a linked list, scheduling, and re-renders.

    8 lessons

  15. Track YDeep track

    Cryptography, under the hood

    The primitives behind every secure system: hash functions, password hashing, symmetric and public-key encryption, MACs and digital signatures, key exchange and forward secrecy, and secure randomness.

    8 lessons

  16. Stage 1

    Core building blocks

    Load balancers, caches, CDNs, object storage, queues, rate limiting.

    4 lessons

  17. Stage 2

    Data & consistency at scale

    Replication, CAP/PACELC, consistency models, quorums, conflicts.

    4 lessons

  18. Stage 3

    Communication & APIs

    REST vs gRPC vs WebSockets, idempotency, pagination, versioning, backpressure.

    5 lessons

  19. Stage 4

    Distributed patterns

    Event-driven systems, outbox, sagas, consensus, the exactly-once myth.

    5 lessons

  20. Stage 5

    Case studies & interview craft

    Worked designs — chat, feed, dispatch, ledger — with the interview framework.

    6 lessons