PyThaiNLP is a Python package for text processing and linguistic analysis, similar to NLTK with focus on Thai language.

Getting Started


PyThaiNLP provides standard NLP functions for Thai, for example part-of-speech tagging, linguistic unit segmentation (syllable, word, or sentence). Some of these functions are also available via command-line interface.

List of Features
  • Convenient character and word classes, like Thai consonants (pythainlp.thai_consonants), vowels (pythainlp.thai_vowels), digits (pythainlp.thai_digits), and stop words (pythainlp.corpus.thai_stopwords) -- comparable to constants like string.letters, string.digits, and string.punctuation
  • Thai linguistic unit segmentation/tokenization, including sentence (sent_tokenize), word (word_tokenize), and subword segmentations based on Thai Character Cluster (subword_tokenize)
  • Thai part-of-speech tagging (pos_tag)
  • Thai spelling suggestion and correction (spell and correct)
  • Thai transliteration (transliterate)
  • Thai soundex (soundex) with three engines (lk82, udom83, metasound)
  • Thai collation (sort by dictionary order) (collate)
  • Read out number to Thai words (bahttext, num_to_thaiword)
  • Thai datetime formatting (thai_strftime)
  • Thai-English keyboard misswitched fix (eng_to_thai, thai_to_eng)
  • Command-line interface for basic functions, like tokenization and pos tagging (run thainlp in your shell)


pip install --upgrade pythainlp

This will install the latest stable release of PyThaiNLP.

Install different releases:

  • Stable release: pip install --upgrade pythainlp
  • Pre-release (near ready): pip install --upgrade --pre pythainlp
  • Development (likely to break things): pip install

Installation Options

Some functionalities, like Thai WordNet, may require extra packages. To install those requirements, specify a set of [name] immediately after pythainlp:

pip install pythainlp[extra1,extra2,...]
List of possible `extras`
  • full (install everything)
  • attacut (to support attacut, a fast and accurate tokenizer)
  • benchmarks (for word tokenization benchmarking)
  • icu (for ICU, International Components for Unicode, support in transliteration and tokenization)
  • ipa (for IPA, International Phonetic Alphabet, support in transliteration)
  • ml (to support ULMFiT models for classification)
  • thai2fit (for Thai word vector)
  • thai2rom (for machine-learnt romanization)
  • wordnet (for Thai WordNet API)

For dependency details, look at extras variable in

Data directory

  • Some additional data, like word lists and language models, may get automatically download during runtime.
  • PyThaiNLP caches these data under the directory ~/pythainlp-data by default.
  • Data directory can be changed by specifying the environment variable PYTHAINLP_DATA_DIR.
  • See the data catalog (db.json) at

Command-Line Interface

Some of PyThaiNLP functionalities can be used at command line, using thainlp command.

For example, displaying a catalog of datasets:

thainlp data catalog

Showing how to use:

thainlp help