I built GPT from scratch to understand how it works
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If you’ve ever been curious about how GPT actually works under the hood, I built a small project you might find interesting. I implemented a GPT-style transformer from scratch in a single notebook—covering tokenization, embeddings, causal self-attention, training, and autoregressive text generation without relying on high-level abstractions. The focus was on mechanistic clarity rather than scale or performance, and the notebook is structured to read more like a technical walkthrough than an experiment log. Feedback from people who’ve built or studied transformers would be very welcome.
HN · launched Jan 14, 2026 · 7 upvotes (top 65%) · 0 views
Niche: gpu infrastructure and developer tools · 129 launches, 7 in the last 7 days ▼ -30% · Explore this niche →
Category and tags
- Education
- Dev tools
- Developer
- AI-native
- Hobby / open-source project
Visit website ↗ Source listing ↗
More like this: all 129 launches in gpu infrastructure and developer tools →
Could you build this?
Yes The author built an educational nanoGPT-style transformer in a single Python notebook using PyTorch. Implementing basic causal self-attention, tokenization, and forward passes is a well-trodden tutorial path that AI assistants can generate comprehensively.
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Competitors
Other products that read as similar to this one : 159 launches clear the similarity bar, closest 8 shown.
Attention rank: #101 of 160 (itself plus its competitors, highest first, normalized so YC and Product Hunt are compared fairly).
Launched 76 days after the earliest competitor.
- Transformer Primitives · hn · 2026-06-23 · 7 upvotes · similarity 0.64
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- microgpt · github · 2026-10-14 · 22 upvotes · similarity 0.50
- tiny-transformer-from-scratch · github · 2026-11-02 · 99 upvotes · similarity 0.50
- Building an LLM from Scratch in TypeScript · hn · 2026-10-14 · 33 upvotes · similarity 0.47
- TurboGPT: train 22KiB transformer in 13s · hn · 2026-09-29 · 56 upvotes · similarity 0.46
- microgpt · github · 2026-11-05 · 51 upvotes · similarity 0.45
- NanoEuler · hn · 2026-06-19 · 6 upvotes · similarity 0.45
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