Building an LLM from Scratch in TypeScript
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I wanted to understand transformers at a level where nothing is magic, so I'm building a ChatGPT-style model from first principles in TypeScript. Why not Python? I've found that reimplementing concepts in a different language forces me to grasp the nuance of the implementation. Chapters cover dataloaders, embeddings, and the attention mechanism so far. Feedback welcome if anything's unclear.
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HN · launched Oct 14, 2026 · 33 upvotes (top 25%)
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- Dev tools
- Developer
- AI-native
- Hobby / open-source project
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See all 302 similar launches →Could you build this?
No Implementing a transformer architecture from scratch in TypeScript requires building custom tensor math, autograd differentiation engines, and numerically stable backpropagation algorithms without modern ML frameworks.
What it would actually take: Building an LLM from scratch in pure TypeScript requires implementing a custom n-dimensional tensor library, automatic differentiation (reverse-mode autograd), CUDA/WebGPU or CPU matrix multiplication optimizations, tokenizer engines (Byte-Pair Encoding), and memory management for model parameters. The primary difficulty is numerical stability in gradient computation and performance optimization, demanding deep expertise in mathematical computing and deep learning internals.
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Competitors
Other products that read as similar to this one : 302 launches clear the similarity bar, closest 8 shown.
Attention rank: #93 of 303 (itself plus its competitors, highest first, normalized so YC and Product Hunt are compared fairly).
Launched 348 days after the earliest competitor.
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