The Apache OpenNLP library is a machine learning based toolkit for the processing of natural language text. It supports the most common NLP tasks, such as tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, chunking, parsing, and coreference resolution. These tasks are usually required to build more advanced text processing services. OpenNLP also included maximum entropy and perceptron based machine learning.

NLP, Tokenizer, Categorizer, OpenNLP, Parser, Chunker, NER, POS, dotnet, fsharp, recompiled-packages
Install-Package OpenNLP.NET -Version 1.9.1


Build status

OpenNLP for .NET NuGet Status

OpenNLP for .NET is a port of OpenNLP to .NET.

This project contains build scripts that recompile OpenNLP .jar packages to .NET assemblies using IKVM.NET and tests that help to be sure that recompiled packages are workable. Recompiled assemblies are available on NuGet.

.NET samples are available in tests. Manual is available on official site.


Versioning model used for NuGet packages is aligned to versioning used by OpenNLP Team. For example, if you get OpenNLP package from OpenNLP site with version 1.5.3, then the NuGet version of this package has a version 1.5.3.x, where x is the greatest that is available on NuGet. Last number is used for internal versioning of .NET assemblies.


Project is licensed under the terms of the Apache 2.0 license