Labels tokens with their POS tag. For more details see this page.

Property name Annotator class name Generated Annotation
pos POSTaggerAnnotator PartOfSpeechAnnotation


  • pos.model: POS model to use. There is no need to explicitly set this option, unless you want to use a different POS model (for advanced developers only). By default, this is set to the english left3words POS model included in the stanford-corenlp-models JAR file.
  • pos.maxlen: Maximum sentence size for the POS sequence tagger. Useful to control the speed of the tagger on noisy text without punctuation marks. Note that the parser, if used, will be much more expensive than the tagger.

Caseless models

It is possible to run StanfordCoreNLP with a POS tagger model that ignores capitalization. We have trained models like this for English. You can find details on the Caseless models page.

More information

The POS tagger is described in detail on the Stanford NLP website.