{"slug": "build-a-tokenizer-from-scratch", "title": "Build a Tokenizer from Scratch", "summary": "Crackr released a free, open-source guide on building a byte-level BPE tokenizer from scratch, culminating in a multilingual encoding compatible with OpenAI's tiktoken and a web playground. The guide includes implementing BPE, optimizing training, saving a .tiktoken model, and shipping it in a playground, with automated evaluations available on Crackr.", "body_md": "Build a byte-level BPE tokenizer from scratch, starting with a simple word tokenizer and working up to a trained multilingual encoding compatible with tiktoken.\n\nAlong the way, you’ll implement BPE, optimize training, train your own tokenizer, save it as a .tiktoken model, and ship it in a small web playground.\n\n**Live demo:** [See what you will build by the end of the guide](https://tokenizer-playground.onrender.com/).\n\nThis repository contains the complete open-source guide. You can also build the project on [Crackr](https://app.crackr.dev/projects/build-your-own-tokenizer), where each step comes with automated evaluations, progress tracking, and interactive playgrounds.\n\nThe full project and all evaluations are free.\n\n[Scale up training](/crackr-org/build-a-tokenizer-from-scratch/blob/main/guide/05-ship-your-tokenizer/01-scale-up-training.md)[Port your tokenizer to tiktoken](/crackr-org/build-a-tokenizer-from-scratch/blob/main/guide/05-ship-your-tokenizer/02-port-your-tokenizer-to-tiktoken.md)[Build a tokenizer playground](/crackr-org/build-a-tokenizer-from-scratch/blob/main/guide/05-ship-your-tokenizer/03-build-a-tokenizer-playground.md)[Where to go from here](/crackr-org/build-a-tokenizer-from-scratch/blob/main/guide/05-ship-your-tokenizer/04-where-to-go-from-here.md)\n\nThis guide is available under the [MIT License](/crackr-org/build-a-tokenizer-from-scratch/blob/main/LICENSE).", "url": "https://wpnews.pro/news/build-a-tokenizer-from-scratch", "canonical_source": "https://github.com/crackr-org/build-a-tokenizer-from-scratch/tree/main", "published_at": "2026-08-30 22:32:46+00:00", "updated_at": "2026-08-30 22:51:41.813463+00:00", "lang": "en", "topics": ["developer-tools", "large-language-models"], "entities": ["Crackr", "OpenAI", "tiktoken"], "alternates": {"html": "https://wpnews.pro/news/build-a-tokenizer-from-scratch", "markdown": "https://wpnews.pro/news/build-a-tokenizer-from-scratch.md", "text": "https://wpnews.pro/news/build-a-tokenizer-from-scratch.txt", "jsonld": "https://wpnews.pro/news/build-a-tokenizer-from-scratch.jsonld"}}