Building a BPE Tokenizer from Scratch in Pure Python

TL;DR — Building a byte‑pair encoding tokenizer in pure Python showcases algorithmic mastery and systems thinking. The implementation covers vocabulary learning, merge‑based subword segmentation, and efficient encode/decode, providing a portfolio piece that signals real NLP engineering skill.

In modern NLP pipelines, tokenization is the first and often overlooked step. A well‑designed tokenizer can reduce vocabulary size, improve model performance, and make training faster. This post walks you through implementing a byte