BERTTokenizers 1.0.3

Install-Package BERTTokenizers -Version 1.0.3
dotnet add package BERTTokenizers --version 1.0.3
<PackageReference Include="BERTTokenizers" Version="1.0.3" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add BERTTokenizers --version 1.0.3
The NuGet Team does not provide support for this client. Please contact its maintainers for support.
#r "nuget: BERTTokenizers, 1.0.3"
#r directive can be used in F# Interactive, C# scripting and .NET Interactive. Copy this into the interactive tool or source code of the script to reference the package.
// Install BERTTokenizers as a Cake Addin
#addin nuget:?package=BERTTokenizers&version=1.0.3

// Install BERTTokenizers as a Cake Tool
#tool nuget:?package=BERTTokenizers&version=1.0.3
The NuGet Team does not provide support for this client. Please contact its maintainers for support.

Contributors Forks Stargazers Issues MIT License LinkedIn

BERTTokenizer for C#

About The Project

While working with BERT Models from Huggingface in combination with ML.NET, I stumbled upon several challenges. I documented them in here.</br> However, the biggest challenge by far was that I needed to implement my own tokenizer and pair them with the correct vocabulary. So, I decided to extend it and publish my implementation as an open-source implementation.

This repository contains tokenizers for the following models: · BERT Base · BERT Large · BERT German · BERT Multilingual · BERT Base Uncased · BERT Large Uncased

Built With

Getting Started

The project is available as a NuGet package.


To add BERT Tokenizers to your project use dotnet command:

dotnet add BERTTokenizers

Or install it with the package manager:

Install-Package BERTTokenizers


For example, you want to use Huggingface BERT Base Model whose input is defined like this:

public class BertInput
    [VectorType(1, 256)]
    public long[] InputIds { get; set; }

    [VectorType(1, 256)]
    public long[] AttentionMask { get; set; }

    [VectorType(1, 256)]
    public long[] TypeIds { get; set; }

For this you need to encode sentences like this:

var sentence = "I love you";

var tokenizer = new BertBaseTokenizer();

var encoded = tokenizer.Encode(256, sentence);

var bertInput = new BertInput()
                    InputIds = encoded.InputIds,
                    AttentionMask = encoded.AttentionMask,
                    TypeIds = encoded.TokenTypeIds,

For more examples, please refer to this Blog Post

See the open issues for a full list of proposed features (and known issues).


Contributions are what makes the open source community such an amazing place to learn, inspire, and create. Any contributions you make are greatly appreciated.

If you have a suggestion that would make this better, please fork the repo and create a pull request. You can also simply open an issue with the tag "enhancement". Don't forget to give the project a star! Thanks again!

  1. Fork the Project
  2. Create your Feature Branch (git checkout -b feature/AmazingFeature)
  3. Commit your Changes (git commit -m 'Add some AmazingFeature')
  4. Push to the Branch (git push origin feature/AmazingFeature)
  5. Open a Pull Request


Distributed under the MIT License. See LICENSE.txt for more information.


Nikola M. Zivkovic LinkedIn @NMZivkovic


  • Gianluca Bertani - Performance Improvements
  • net5.0

    • No dependencies.

NuGet packages

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Version Downloads Last updated
1.0.3 195 10/31/2021

Open-source project for BERT tokenizers that can be used in C#.