  We present PyThaiNLP, a free and open-source natural language processing
(NLP) library for Thai language implemented in Python. It provides a wide range
of software, models, and datasets for Thai language. We first provide a brief
historical context of tools for Thai language prior to the development of
PyThaiNLP. We then outline the functionalities it provided as well as datasets
and pre-trained language models. We later summarize its development milestones
and discuss our experience during its development. We conclude by demonstrating
how industrial and research communities utilize PyThaiNLP in their work. The
library is freely available at https://github.com/pythainlp/pythainlp.
