Study. Practice. Walk in ready.

Learn how production AI systems work,
and walk into the interview ready.

Clear explanations, diagrams, and real interview questions on RAG, agents, inference, and evaluation. Written to go deep, not skim.

11
in depth topics
46
diagrams
Always current
updated as the field moves

What you will learn

Start anywhere. Each topic is self contained, with diagrams and interview questions.

foundations

How LLMs Actually Work

A ground-up tour of tokens, embeddings, attention, and why transformers scale.

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model landscape

Choosing the Right Model

A practical framework for navigating the 2026 model landscape and picking the right model for your use case, budget, and latency requirements.

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training and adaptation

Fine-Tuning and Adaptation

How to adapt pretrained language models to specific tasks using full fine-tuning, LoRA, instruction tuning, and preference alignment, and when each approach is the right tool.

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inference optimization

Inference Optimization

How LLM serving works under the hood, and the techniques that make it fast, cheap, and scalable in production.

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prompting and context

Prompting and Context Engineering

How to structure prompts and fill the context window so models produce reliable, grounded, and cost-efficient outputs.

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retrieval

RAG Fundamentals

Why retrieval-augmented generation works, and how to build a pipeline that actually grounds answers.

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agents

Agent Fundamentals

From single LLM calls to autonomous agents: planning, tool use, memory, and the control loop.

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memory and state

Memory and State

How AI systems store, retrieve, and manage information across tiers, from the context window to persistent knowledge stores.

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reliability and safety

Reliability and Safety

How to build AI pipelines that fail gracefully and refuse to produce harm, from input guardrails to circuit breakers to ensemble verification.

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evaluation and observability

Evaluating AI Systems

How to measure, monitor, and improve LLM system quality from offline eval sets through production observability.

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ai design patterns

AI Design Patterns

A catalog of recurring architectural patterns for LLM systems, with tradeoffs, failure modes, and guidance on when to combine or avoid each.

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Why this guide

Built to help you pass the technical screen and system design rounds.

Interview ready depth

Every topic goes past the summary into tradeoffs, failure modes, and worked examples you can defend in a panel.

Clear visual models

Each concept comes with a diagram, so the mental model sticks instead of a wall of text.

Active recall built in

Each chapter ends with real interview questions and model answers, so you practice retrieving, not just reading.

Kept current

The material tracks how production AI systems are actually built today, not how they looked years ago.

See the concept, not just the words

A sample from the agents chapter.

THINK → ACT → OBSERVE, the ReAct cycle that drives every autonomous agent
THINK → ACT → OBSERVE, the ReAct cycle that drives every autonomous agent

What learners say

Feedback from engineers preparing for AI system design interviews.

The interview questions at the end of each chapter were the closest thing to my actual onsite. I stopped memorizing and started reasoning, and it showed in the panel.
Arjun MehtaSenior Backend Engineer
I had read about retrieval a dozen times and still could not draw it. The diagrams here finally made the whole pipeline click in one sitting.
Priya NairML Engineer
Most resources stay at the surface. This one explains why each choice is made, which is exactly what staff interviews push on.
Daniel OkaforStaff Software Engineer
The inference optimization chapter alone changed how I talk about serving cost in design rounds. Concrete numbers, no hand waving.
Sofia AlmeidaPlatform Engineer
Clear, current, and honest about tradeoffs. I used it to prep for two AI infra interviews and felt ready for both.
Wei ChenSenior ML Infrastructure Engineer
The reliability and evaluation chapters are things I now reference at work, not just for interviews. That is rare for free material.
Hannah SchmidtAI Engineering Lead

Questions

Who is this for

Engineers and practitioners preparing for AI system design interviews, and anyone who wants a clear working model of how these systems fit together.

Do I need an account

No. Everything is open and free to read.

How deep does it go

Past the summary. Each topic covers tradeoffs, failure modes, and a worked example, then ends with interview questions and model answers.

Is the content kept up to date

Yes. It tracks how production AI systems are built today and is revised as the field moves.

Get in touch

Questions, corrections, or want to suggest a topic, send a note.