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Language Model Builder is a 100% free, no-account app that runs entirely offline…

Brief

Language Model Builder is a free, offline app that teaches and runs small LM training locally. It pairs a 90‑minute interactive textbook (tokenization, embeddings, attention, transformers, loss, fine-tuning) with a workbench on Apple's MLX to pretrain, SFT fine‑tune, and DPO-align models, show live loss curves and token-probability x‑rays; default runs produce coherent multi‑paragraph text in about a day.

Why it matters

Language Model Builder is a 100% free, no-account app that runs entirely offline and is delivered in two parts: a 90-minute interactive textbook and a local training workbench targeting Apple's MLX.

Key details

  • The interactive textbook covers tokenization, embeddings, attention, the transformer, training data, loss and gradient descent, and fine-tuning, with runnable experiments and no coding or math background required.
  • The workbench runs a full local pipeline—pre-train a base model on a chosen dataset, fine-tune with SFT, align with DPO, display live loss curves and a token-probability x‑ray; default settings yield coherent multi-paragraph output in ~1 day, while a GPT-2-small-class model takes roughly ~1 week on a high-end Mac.
Source evidence

you can build your own small language model from scratch on your computer - this free app walks you through every step 🤯

it's called Language Model Builder, and it comes in two parts.

the first is a 90-minute interactive textbook. 

it covers the fundamentals, tokenization, embeddings, attention, the transformer, training data, loss and gradient descent, fine-tuning. no coding or math background needed.

and instead of staring at diagrams, you run each experiment yourself as you read.

the second is a training workbench that runs the full pipeline locally on Apple's MLX:

> pre-train a base model on a dataset you pick
> fine-tune it with SFT, then align it with DPO
> watch the loss curve drop in real time as it learns
> chat with the model you made, with a token-probability x-ray view so you can see how it "thinks"

on default settings you'll get coherent, multi-paragraph text in about a day. 

a GPT-2-small-class model takes roughly a week on a high-end Mac. 

100% free, no account, runs entirely offline.

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