Coding LLMs from the Ground Up: A Complete Course

I wrote a lot about reasoning models in recent months (4 articles in a row)! Next to everything "agentic," reasoning is one of the biggest LLM topics of 2025.

This month, however, I wanted to share more fundamental or "foundational" content with you on how to code LLMs, which is one of the best ways to understand how LLMs work.

Why? Many people really liked and benefited from the abbreviated LLM workshop I shared last year:

So, I thought this ~5× longer and more detailed content (~15 hours in total) would be even more useful.

Also, I'm sadly dealing with a bad neck injury and haven't really been able to work on a computer for the past 3 weeks. I am currently trying a conservative treatment before considering the suggested surgical route. This is the worst timing as I just started to get back on track before life threw another curveball.

So, during my recovery, I thought sharing these videos I recorded in the last couple of months would be a nice in-between content.

I hope you find this useful, and thanks for your support!

PS: The videos originally started as supplementary content for my Build a Large Language Model (From Scratch) book. But it turns out they also work pretty well as standalone content.

Why build from scratch?

It's probably the best and most efficient way to learn how LLMs really work. Plus, many readers have told me they had a lot of fun doing it.

To offer an analogy: if you are into cars and want to understand how they work, following a tutorial that walks you through building one from the ground up is a great way to learn. Of course, we probably wouldn't want to start by building a Formula 1 race car since it would be prohibitively expensive and overly complex for a first project. Instead, it makes more sense to start with something simpler, like a go-kart.

Building a go-kart still teaches you how the steering works, how the motor functions, and more. You can even take it to the track and practice (and have a lot of fun with it) before stepping into a professional race car (or joining a company or team that is focused on building one). After all, the best race drivers often got their start by building and tinkering with their own go-karts (think Michael Schumacher and Ayrton ...