Sebastian Raschka Ports 'LLM From Scratch' to JAX and Preps 'Build a Reasoning Model (From Scratch)'

Sebastian Raschka·low signal

On July 8 Raschka published part 34b of his from-scratch series — rebuilding the path from bigrams to GPT-2 one component at a time in JAX — while opening pre-orders for a follow-up book, 'Build a Reasoning Model (From Scratch),' teaching how reasoning LLMs actually work under the hood. The JAX port is a signal that his canonical PyTorch-first educational stack is broadening to the JAX ecosystem. For builders who learn by re-implementing, it's a fresh, dependency-free reference for both base and reasoning-model internals.