Apache Lucene.NET

Clone this repo:
  1. ece6bea Update home-quick-start.tmpl.partial by Antony Corbett · 2 days ago master
  2. b8ab1eb azure-pipelines.yml: Added tests for .NET Framework x86 (see #258) by Shad Storhaug · 2 days ago
  3. de5251c Lucene.Net.Search.FieldCacheImpl: Added comments to indicate where and why we have diverged from Lucene 4.8.0 by Shad Storhaug · 4 days ago
  4. a2fac85 mark new fields as private by rafael-aero · 4 days ago
  5. 20bd304 remove unecessary dictionary lookup by rafael-aero · 4 days ago

Apache Lucene.NET

Nuget Azure DevOps builds (master) GitHub

Full-text search for .NET

Apache Lucene.NET is a .NET full-text search engine framework, a C# port of the popular Apache Lucene project. Apache Lucene.NET is not a complete application, but rather a code library and API that can easily be used to add search capabilities to applications.

The Apache Lucene.NET web site is at: http://lucenenet.apache.org

Supported Frameworks

Lucene.NET 3.0.3

  • .NET Framework 4.0
  • .NET Framework 3.5

Lucene.NET 4.8.0


Latest Stable Version: Lucene.NET 3.0.3

Working toward Lucene.NET 4.8.0 (currently in BETA)


Lucene.NET 3.0.3

Core Library

NuGet version

PM> Install-Package Lucene.Net
All Packages

Lucene.NET 4.8.0

Core Library

NuGet version

PM> Install-Package Lucene.Net -Pre
All Packages


We now have some preliminary documentation for Lucene.NET 4.8.0 on the Lucene.NET Website.

The API is similar to Java Lucene 4.8.0, which you may also find helpful to review.

NOTE: We are working on fixing issues with the documentation, but could use more help since it is a massive project. See #206.

Legacy Versions

Demos & Tools

There are several demos implemented as simple console applications that can be copied and pasted into Visual Studio or compiled on the command line in the Lucene.Net.Demo project.

There is also a dotnet command line tool available on NuGet. It contains all of the demos as well as tools maintaining your Lucene.NET index, featuring operations such as splitting, merging, listing segment info, fixing, deleting segments, upgrading, etc. Always be sure to back up your index before running any commands against it!

dotnet tool install lucene-cli -g --version 4.8.0-beta00012

Once installed, you can explore the commands and options that are available by entering the command lucene.

lucene-cli Documentation

How to Contribute

We love getting contributions! Read our Contribution Guide or read on for ways that you can help.

Join Mailing Lists

How to Join Mailing Lists

Ask a Question

If you have a general how-to question or need help from the Lucene.NET community, please subscribe to the user mailing list by sending an email to user-subscribe@lucenenet.apache.org and then follow the instructions to verify your email address. Note that you only need to subscribe once.

After you have subscribed to the mailing list, email your message to user@lucenenet.apache.org.

Alternatively, you can get help via StackOverflow's active community.

Please do not submit general how-to questions to GitHub, use GitHub for bug reports and tasks only.

Report a Bug

To report a bug, please use the GitHub issue tracker.

NOTE: In the past, the Lucene.NET project used the JIRA issue tracker, which has now been deprecated. However, we are keeping it active for tracking legacy issues. Please submit any new issues to GitHub.

Start a Discussion

To start a development discussion regarding technical features of Lucene.NET, please email the dev mailing list by sending an email to dev-subscribe@lucenenet.apache.org and then follow the instructions to verify your email address. Note that you only need to subscribe once.

After you have subscribed to the mailing list, email your message to dev@lucenenet.apache.org.

Submit a Pull Request

Before you start working on a pull request, please read our Contributing guide.

Building and Testing

Command Line

Building on the Command Line is currently only supported on Windows.

  1. Powershell 3.0 or higher (see this question to check your Powershell version)
  2. .NET Core SDK 3.1 or higher
  3. .NET Framework 4.8 Developer Pack

To build the source, clone or download and unzip the repository. From the repository root, execute:

> build [options]
Build Options

NuGet packages are output by the build to the /release/NuGetPackages/ directory. Test results (if applicable) are output to the /release/TestResults/ directory.

You can setup Visual Studio to read the NuGet packages like any NuGet feed by following these steps:

  1. In Visual Studio, right-click the solution in Solution Explorer, and choose “Manage NuGet Packages for Solution”
  2. Click the gear icon next to the Package sources dropdown.
  3. Click the + icon (for add)
  4. Give the source a name such as Lucene.Net Local Packages
  5. Click the ... button next to the Source field, and choose the /src/release/NuGetPackages folder on your local system.
  6. Click Ok

Then all you need to do is choose the Lucene.Net Local Packages feed from the dropdown (in the NuGet Package Manager) and you can search for, install, and update the NuGet packages just as you can with any Internet-based feed.

Visual Studio


  1. Visual Studio 2019 or higher
  2. .NET Core SDK 3.1 or higher
  3. .NET Framework 4.8 Developer Pack


  1. Open Lucene.Net.sln in Visual Studio.
  2. Choose the target framework to test by opening build/TestTargetFramework.proj and uncommenting the corresponding <TargetFramework>.
  3. Build a project or the entire solution, and wait for Visual Studio to discover the tests - this may take several minutes.
  4. Run or debug the tests in Test Explorer, optionally using the desired filters.

NOTE: When running tests in Visual Studio, be sure to set the default processor architecture to 64 bit to avoid running out of virtual memory on some tests.

Azure DevOps

We have setup our azure-pipelines.yml file with logical defaults so anyone with an Azure DevOps account can build Lucene.Net and run the tests with minimal effort. Even a free Azure DevOps account will work, but tests will run much faster if the account is setup as public, which enables up to 10 parallel jobs to run simultaneously.


  1. An Azure DevOps account.
  2. A fork of this repository either on GitHub or Azure DevOps. The rest of these instructions assume a GitHub fork.


If you don't already have a pipeline set up:
  1. Create an Azure DevOps organization. If you already have one that you wish to use, you may skip this step.
  2. Create an Azure DevOps project. We recommend naming the project Lucene.NET. Note that if you are using a free Azure DevOps account, you should choose to make the project public in order to enable 10 parallel jobs. If you make the project private, you will only get 1 parallel job. Also, if disabling features, make sure to leave Pipelines enabled.
  3. Create an Azure DevOps pipeline.
    • Click on “Pipelines” from the left menu.
    • Click the “Create Pipeline” or “New Pipeline” button, depending on whether any pipelines already exist.
    • Select GitHub as the location to find the YAML file.
    • Select the fork of this repository you created in “Prerequisites”. Note that if this is a new Azure DevOps account you may need to setup extra permissions to access your GitHub account.
    • Next a “Review your YAML” page is presented showing the contents of azure-pipelines.yml. There is documentation near the top of the file indicating the variables that can be setup to enable additional options, but note that the default configuration will automatically run the build and all of the tests.
    • Click the “Run” button at the top right of the page.
If you already have a pipeline set up:
  1. Click on “Pipelines” from the left menu.
  2. Select the pipeline you wish to run.
  3. Click the “Queue” button on the upper right.
  4. (Optional) Select the branch and override any variables in the pipeline for this run.
  5. Click the “Run” button.

Note that after the build is complete, the nuget artifact contains .nupkg files which may be downloaded to your local machine where you can setup a local folder to act as a NuGet feed.

It is also possible to add an Azure DevOps feed id to a new variable named ArtifactFeedID, but we are getting mixed results due to permission issues.