Free · No sign-up · Beginner to interview
A step-by-step roadmap from how LLMs work to RAG, agents and shipping to production, and on to the interview. Every topic is an animated video, a written lesson and a quick quiz.
Beginner 4:23 video
§ 01
Five stages, from your first look at how a language model works to designing AI systems in an interview. Each lesson needs only the ones before it.
Stage 01 · Beginner
What an AI engineer does, how a language model turns text into an answer, how to pick one, and how to talk to it with prompts and code.
9 of 26 lessons live
Stage 02 · Intermediate
Give a model your own documents with embeddings and RAG, then prove your app works with evals.
4 of 19 lessons live
Stage 03 · Advanced
Models that plan, call tools and check their own work: the agent loop, MCP, multi-agent systems and context engineering.
4 of 17 lessons live
Stage 04 · Advanced
Ship it safely and keep it fast, cheap and correct: security, observability, serving, fine-tuning and multimodal.
0 of 22 lessons live
Stage 05 · Interview
Put it all together the way interviews ask: design a real AI system end to end and defend each trade-off.
0 of 6 lessons live
Every topic, in order, with your progress.
See the full roadmap§ 02
Every lesson gives you three ways into the same idea, because understanding sticks when you see it, read it and use it.
01 · Watch
A short animated explainer, narrated, with Vora as your guide: diagrams move, data flows, code runs.
02 · Read
What you'll learn
What to know first: what a large language model is ([What is an LLM?](/ai-engineering/what-is-an-llm/)) and that your app reaches one over the internet with an API call, a request your code sends to the model's company, which sends an answer back. That's all you need.
A written deep dive at your own pace, with code that has been run before it was published.
03 · Practice
Aaryan's main model has been down for an hour. Which change helps customers most right now?
A short quiz that explains every answer, right or wrong.
See the whole lesson: When a Cloud Provider Goes Down: Keep Your AI App Running
§ 03
New lessons are added as they pass review.
4:06AI Engineering Beginner 10 min read
Every cloud goes down sometimes, even Microsoft's. See why an app that calls one AI model in one cloud fails with it, and the moves that keep it taking orders.
Nov 13, 2026
4:40AI Engineering Beginner 11 min read
Three job titles, the same tools in every ad. Ask what each one hands over at the end: an answer, a model trained on your own data, or a product built on a ready-made model.
Nov 12, 2026
4:29AI Engineering Beginner 11 min read
A model that has only read the internet won't answer you; it continues your text. Learn the three training stages that turn a next-word guesser into a helpful assistant, and what each one can't do.
Nov 9, 2026
4:23AI Engineering Beginner 4 min read
An AI engineer takes a ready-made AI model and builds a real product around it. One small lunch-box business shows the three jobs that turn a guessing chat assistant into one you can trust.
Nov 9, 2026
6:44AI Engineering Beginner 5 min read
An AI chat never has a finished answer waiting. It scores every possible next token, picks one, adds it to the text and runs again, until it picks a stop token.
Oct 31, 2026
7:16AI Engineering Beginner 5 min read
An LLM never reads letters or whole words. It reads tokens: pieces of text, each swapped for a number. Here's how that works, and why it decides limits, prices and spelling mistakes.
Oct 29, 2026
§ 04
Developers and students who want to become AI engineers, and engineers preparing for AI engineering interviews. You can start from zero: the roadmap goes one topic at a time, and each lesson builds only on the ones before it.
Yes. Every lesson, video and quiz is free. No paywalls, no pop-ups.
No, there's no sign-up. When you mark a lesson as done, that's saved in your browser only, so it stays on this device and nothing is sent to us.
An animated, narrated video with captions, a written deep dive with callouts and key takeaways, code that is run in a sandbox before it's published, and a short quiz.
Each lesson starts from the author's own notes. Every claim is checked, every code example is run in a sandbox, and the author reviews and signs off on each lesson before it goes live.
There's no fixed schedule: new lessons are added as they pass review. The RSS feed, linked in the footer, announces each one.
Email support@codestoa.com if something isn't working, like a video that won't play or a broken link. Email feedback@codestoa.com to report a mistake in a lesson or suggest a topic. The author reads every message.