# Show HN: Every number in a tiny GPT, from one forward pass to one step of RLHF

> Source: <https://llm.manogya.dev>
> Published: 2026-10-07 11:44:37+00:00

Source: [https://github.com/manogyasingh/transformer-visualisation](https://github.com/manogyasingh/transformer-visualisation)
Made this with Opus 5.5 to understand the exact working of an LLM.

It's a step by step walkthrough of a toy GPT-2 like model. Every matrix fits on screen, every number is computed live in the browser, and hovering over any cell shows the exact math of that step. It covers inference -- following the generation of one token from tokensiation to sampling, one training step of pretraining, and one PPO iteration of RLHF for post-training.

Inspired in part by Brendan Bycroft's LLM visualization ([https://bbycroft.net/llm](https://bbycroft.net/llm))

Comments URL: [https://news.ycombinator.com/item?id=49991390](https://news.ycombinator.com/item?id=49991390)

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