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Backend cheat sheets

Backend cheat sheets on Sefism, written by Tauseef Fayyaz: every concept in plain words, why it is used and the pitfall that catches people out.

  • 76 sheets
  • 5120 concepts

Free to learn. Credits keep it fair.

Reading is free. Adding a roadmap, keeping a cheat sheet or asking Tauseef a question uses credits, which only make sure the platform goes to people who are actually learning.

  • 15creditswhen you join
  • 1stroadmapfree to add
  • Morecreditson request, as you learn

Foundations

1

Start here if you are new or your basics are patchy.

  • Cheat sheet · Foundations

    MongoDB cheat sheet

    Documents, modelling, indexes, aggregation.

    Chapters

    1. 1Documents and your setup
    2. 2Reading and writing documents
    3. Arrays and nested documents

    + 5 more

    • 8 chapters
    • 77 concepts
    Opens with credits

Build products

4

Ship real apps for the web and phones.

  • Cheat sheet · Build products

    Full stack development cheat sheet

    Build and ship whole web apps.

    Chapters

    1. 1Web foundations: HTTP, HTML, CSS and JavaScript
    2. 2Git, npm and React
    3. APIs, authentication and caching

    + 2 more

    • 7 chapters
    • 58 concepts
    Opens with credits

  • Cheat sheet · Build products

    .NET developer cheat sheet

    C#, ASP.NET Core, EF Core, production-ready APIs.

    Chapters

    1. 1C# syntax you use every day
    2. 2LINQ
    3. async, await and Tasks

    + 7 more

    • 10 chapters
    • 78 concepts
    Opens with credits

Specialise

4

Go deep in one area of engineering.

  • Cheat sheet · Specialise

    System design cheat sheet

    Systems that scale.

    Chapters

    1. 1Core concepts: scale, latency and availability
    2. 2Load balancing, proxies, CDNs and caching
    3. Databases: models, indexes and transactions

    + 7 more

    • 10 chapters
    • 79 concepts
    Opens with credits

  • Cheat sheet · Specialise

    AI agents and MCP cheat sheet

    Tool calling, MCP servers, evals.

    Chapters

    1. 1How agents work
    2. 2Tool calling from scratch
    3. Structured output and validation

    + 7 more

    • 10 chapters
    • 74 concepts
    Opens with credits

  • Cheat sheet · Specialise

    RAG cheat sheet

    Retrieval augmented generation end to end: chunking, embeddings, hybrid retrieval, reranking, grounded prompts, evaluation and failure modes.

    Chapters

    1. 1RAG basics
    2. 2Loading and chunking
    3. Embeddings and the index

    + 5 more

    • 8 chapters
    • 54 concepts
    Opens with credits

  • Cheat sheet · Specialise

    GenAI app architecture cheat sheet

    How a production GenAI app fits together: request flow, layers, RAG, agent loop, memory, caching, guards, evals, tracing, folder layout and launch checklist.

    Chapters

    1. 1The request flow
    2. 2Frontend and backend layers
    3. The RAG pipeline

    + 7 more

    • 10 chapters
    • 58 concepts
    Opens with credits

Browse the cheat sheets by topic

Each of these is its own page: the foundations shelf, the career shelf, the sheets that are open end to end. The filters above do the same thing without a page load.

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