Justin Angel released a complete YouTube workshop teaching you how to build your own large language model from scratch (based on GPT-2 and Qwen3.6 style), covering Transformer architecture, training pipeline, and providing Excel manual operations and Python/PyTorch code practice, with no prerequisites in math or ML.
Hi internet friends, I recorded a workshop about building your own LLM without any math / ML prerequisites. It covers everything from machine learning fundamentals, deep neural networks, transformer architecture, and pre/post-training. The only prerequisite is being comfortable with learning through code & excel examples. 1. [**Sampling** Large Language Models](https://www.youtube.com/watch?v=vXiB0UdDhk8&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 2. [**Reverse Engineering** Large Language Model](https://www.youtube.com/watch?v=E0rkgxwhz5g&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 3. [**Perceptrons:** wx+b](https://www.youtube.com/watch?v=uaA8ChGcMwE&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 4. [**Activation Functions:** ReLU, GELU, SwiGLU](https://www.youtube.com/watch?v=G5gkYVB-P-Q&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 5. [**GPU Coding:** PyTorch, torch.compile(), fused kernels, CUDA, Triton](https://www.youtube.com/watch?v=VVk6N1_rFD0&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 6. [**MLPs/FFNs**: Multi-input, Multi-Layer Perceptrons, Feed-Forward Networks](https://www.youtube.com/watch?v=6BU9Gj2yoSw&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 7. [**Loss Functions**: Residual errors, RMSE, Cross Entropy, Loss Landscapes](https://www.youtube.com/watch?v=bVz8i9EWEQw&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 8. [**Backpropagation**: Training loops, Optimizers, Learning Rate, Batch Size](https://www.youtube.com/watch?v=Zf6RC6KZxKg&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 9. [**Saving & Loading** Models](https://www.youtube.com/watch?v=riCiHjVEqXc&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 10. [**Initialization**: Kaiming, Glorot](https://www.youtube.com/watch?v=-pwr0RMhCg8&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 11. [**Residuals**: Addition, Scaling, Gated, Concatenation](https://www.youtube.com/watch?v=e5V7QaHq5lQ&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 12. [**Normalization**: Pre-norm vs. Post-norm, RMSNorm, BatchNorm, LayerNorm](https://www.youtube.com/watch?v=ZqSbev8Y-ys&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 13. [**Regularization**: Dropout, Gradient Clipping, Weight Decay](https://www.youtube.com/watch?v=2O8v8BX1LgM&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 14. [**SoftMax**](https://www.youtube.com/watch?v=H2yV3jd4DKg&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 15. [**Tokenizers**: By Character, By Word, BPE, SentencePiece](https://www.youtube.com/watch?v=TPPhTqPu_Yg&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 16. [**Embeddings**: Absolute vs. Learned, Sinusoidal vs. RoPE](https://www.youtube.com/watch?v=jyrgYjeVHBo&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 17. [**Attention**: MHA, GQA, MQA, MLA](https://www.youtube.com/watch?v=CvGf-Eu2sl0&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 18. [**Transformers**](https://www.youtube.com/watch?v=mKAW7cYYwQs&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 19. [**Pre-training**: Data Sources, Datasets, HTML Cleaning, Quality Filtering, Sharding ](https://www.youtube.com/watch?v=nN335-483Pg&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 20. [**Evaluation**: Leaderboards, Benchmarks, Verifiers vs LLM-as-Judge ](https://www.youtube.com/watch?v=S6uLzsqOOUc&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 21. [**Instruction Tuning:** Alpaca & Other Formats, Self Instruct, Capabilities](https://www.youtube.com/watch?v=8iwxM6XRpVQ&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 22. [**Reinforcement Learning:** Policy Optimization, SimPO](https://www.youtube.com/watch?v=3DJGUp0CVx8&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) 23. [What We Didn't Cover: Scaling ](https://www.youtube.com/watch?v=YdOsmHDeeLw&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6) Each section has slides teaching the concepts, followed by excel-by-hand developing intuition for the math, and then coding examples. The goal is able to grok all parts of modern LLM development. We did this workshop [in-person in San Francisco](https://emilyhk.com/llm-workshop/) last month and hopefully the spaciousness of watching online works for everyone. If don't like watching videos, you can get the [slides and exercises](https://go.JustinAngel.ai/deck) and work self-paced.
# TL;DR Summary
This workshop teaches you how to build your own large language model (LLM) from scratch, with no math or machine learning prerequisites—just familiarity with programming. Through intuitive intuition-building, manual Excel demonstrations, and hands-on Python/PyTorch code, you’ll understand the Transformer architecture, the training pipeline, and finish with a working mini LLM.
## Why Build Your Own Large Language Model?
Why spend hours on this deep technical workshop? The core answer is: **Develop taste and intuition for how AI and ML models are built.** You’ll understand:
- There’s no magic behind these models—everything is math and backpropagation.
- You’ll know the limitations of models, which is critical if you're building applications or agents on top of them.
- You’ll be able to write all the machine learning code and LLM architecture code, and know how to handle pre-training and post-training.
- You can read the code of open-source models (like nano chat, etc.) and gain transferable skills for working on AI/ML solutions.
- When DeepSeek releases a model that moves the stock market, you’ll understand what sparse attention vs. dense attention means.
This workshop alone won’t get you hired at a frontier lab, but it provides all the foundations needed for those roles: GPU programming, AI safety, and other subfields all depend on this knowledge.
## Prerequisites and Non-Prerequisites
**Required**: Software engineer, comfortable with coding, able to spend 8 hours reading code and learning new concepts.
**Not required**:
- Math: Linear algebra, calculus, statistics, etc., are not required—we’ll build intuition in one day, not proofs.
- Python: Helpful but not necessary—we minimize Python usage, use cross-language idioms, and by 2026 you can use AI to read/write code.
- Machine learning: No prior knowledge of perceptrons, neurons needed—all concepts will be covered.
## About the Instructor, Justin Angel
23 years of software engineering experience at Meta, Uber, Amazon, Apple, Microsoft; held IC8 (Meta director-level IC). All code written by AI in 2023-2024. Firm believer that “any software engineer who can’t understand AI at a fundamental level will soon be unemployable.” Recently earned an AI/ML master’s degree with a thesis on LLM psychotherapy. Emphasizes he’s not a 20-year ML engineer, but offers a practical perspective.
## Learning Methodology: Manual AI + Code Practice
The workshop is divided into ~23 parts, each with three phases:
1. **Concept Explanation**: Instructor uses slides to explain the problem, how the technique fits into the big picture, and builds intuition.
2. **Manual AI**: In Excel (Google Sheets), manually perform matrix multiplication, move numbers, and build intuition from a mathematical perspective. This method thanks Professor Tom Yey from the University of Colorado Boulder.
3. **Code Review**: Each part comes with a Python/PyTorch notebook based on the slides and Excel content. The instructor walks through each section.
**Your responsibilities**:
- Fill in the version of the Excel without answers.
- Run, tweak, and read the Colab notebooks.
- Complete 1–3 exercises per part (about 15–20 minutes) and understand the answers.
## Workshop Schedule
### Introduction: Using an Existing GPT-2 Style Transformer
Take an off-the-shelf GPT-2 style Transformer and run it, understand concepts like autoregressive loops, and build the full-day roadmap.
### Machine Learning Basics: Starting with a Single Neuron
- What is a neuron?
- How to train a network?
- What is a loss function?
- How to use gradient descent?
Deliverable: A trained deep neural network (not a language model), with all concepts 100% transferable to large language models.
### Transformer Architecture: Learn Components One by One and Combine
- Multi-Layer Perceptron (MLP)
- Dropout
- Tokenizer
- Embedding Layer
- Attention Mechanism
Finally, assemble all components into the full Transformer architecture.
### LLM Delivery: Pre-training and Post-training
Write post-training and pre-training scripts. By the end of the day, have your own working large language model, branded with your name and version V1.
## Workshop Resource Links
All resources follow a simple naming convention:
- Slides: `go.justinangel.ai/deck`
- Code notebooks: `go.justinangel.ai/code-{part number}`
- Excel spreadsheets: `go.justinangel.ai/excel-{part number}`
- Master link (includes all links): `go.justinangel.ai/drive`
## Start Training Immediately: Part Zero
Because training a large language model takes 8–20 hours, we need to kick off training right at the start of the workshop. Go to `go.justinangel.ai/code-zero`, connect an A100 GPU (requires Google Colab Pro Plus), click “Run All”, and the model will run in the background for 20+ hours. That way, by the end of the workshop, you’ll have your own model!
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**Source**: Hi Reddit, I posted my Build Your Own LLM workshop to Youtube (GPT2 & Qwen3.6 style) (https://www.youtube.com/watch?v=vXiB0UdDhk8&list=PLweJS2YZCfkeXXdfCKGaxAhm2w8p0u1z6&index=1)
LLMs-from-scratch is a GitHub repository that accompanies the book "Build a Large Language Model," providing complete code to implement GPT from scratch with PyTorch, covering the full pipeline including pretraining, fine-tuning, and RLHF. It has gained 93K+ stars and is ideal for developers who want to deeply understand the principles behind large language models.
Recommended a GitHub repo for building a GPT-style Transformer from scratch without advanced libraries. With 13M parameters, it can be trained in one day on free Colab to generate grammatically correct text.
EveryonesLLM is an open-source tutorial that provides 29 chapters of Colab notebooks. It teaches users step by step to build a complete large language model from scratch on Google Colab, including pre-training and instruction fine-tuning, and supports Chinese.
Release of free workshop recordings and materials (23 videos, 250 slides, 50 exercises) for building your own LLM from fundamentals to transformer architecture, with no math or ML prerequisites.
This step-by-step tutorial details how to use OpenAI's GPT-Live for English speaking practice, including assessing your level, scenario-based exercises, and review steps, with ready-to-use prompts provided.