LSP4IJ is a free and open-source Language Server protocol (LSP) client compatible with all flavours of IntelliJ.

It allows you to integrate any language server that communicates with its client via stdio:

• by developing an IntelliJ plugin with LSP extension points:
  • com.redhat.devtools.lsp4ij.server extension point to define a language server.
  • com.redhat.devtools.lsp4ij.languageMapping to associate an IntelliJ language with a language server definition.
• by manually adding language server definitions, supporting custom server settings. This approach doesn't require developing a specific IntelliJ plugin.

LSP4IJ also provides:

• an LSP Consoles view to tracks LSP requests, responses and notifications in a console:

If you select the language server node, you can configure it the same way as in the Language Servers preferences page

and use the left toolbar to Apply or Reset the settings.

• a Language Servers preferences page to configure the LSP trace level, the debug port to use to debug language server:

You can find more documentation in:

• the developer guide, providing step-by-step instructions on how to integrate a language server in LSP4J in an external IntelliJ plugin.
• the User-defined language server documentation, explaining how to integrate a language server in LSP4J with few settings.
• the user guide, which explains how to use LSP console and Language Server preferences.
• the LSP Support overview, describing which LSP features are implemented, and how.

• Meet LSP4IJ, a new LSP Client for JetBrains-based IDEs

Here are some projects that use LSP4IJ:

• Quarkus Tools for IntelliJ
• Inga for IntelliJ
• IntelliJ SumnekoLua

• Intellij IDEA 2023.2 or more recent (we try to support the last 4 major IDEA releases)
• Java JDK (or JRE) 17 or more recent

This is an open source project open to anyone. Contributions are extremely welcome!

Project is managed by Gradle. So building is quite easy.

Run the following command:

./gradlew buildPlugin

The plugin distribution file is located in build/distributions.

You can also easily test the plugin. Just run the following command:

./gradlew runIde

You can also download and install CI builds of the latest commits or a specific pull request:

• open the Build plugin zip workflow
• click on the build you are interested in
• scroll down and download the LSP4IJ <version>.zip file
• install LSP4IJ <version>.zip into IntelliJ IDEA by following these instructions.

You can easily install nightly builds from the nightly channel:

• in IntelliJ, open Setting > Plugins > [Gear icon] > Manage Plugin Repositories...
• Add https://plugins.jetbrains.com/plugins/nightly/23257 and press OK

Nightly builds are published once a day.

If the Red Hat Telemetry plugin is installed, the LSP4IJ plugin will collect anonymous usage data and send it to Red Hat servers to help improve our products and services. Read our privacy statement to learn more. This extension respects the Red Hat Telemetry setting which you can learn more about at https://github.com/redhat-developer/intellij-redhat-telemetry#telemetry-reporting

File a bug in GitHub Issues.

You can have 2 kinds of errors:

• an error from LSP4IJ, in this case, the error will be reported in the standard IntelliJ log.
• an error coming from the language server.

For the second case, you can customize the error reporting with the Debug / Error reporting combo box by opening the Languages & Frameworks / Language Servers preferences:

You can select:

• None : in this case the language server error will be ignored.
• In notification (default value) : in this case the language server error appear as a notification: The error notification shows 3 possible actions:
  • Disable error reporting : sets the error reporting to None.
  • Report error in Log : sets the error reporting to In log.
  • Open LSP4IJ documentation : opens this documentation.
• In log : in this case the language server error will be logged in the standard IntelliJ log:

You can see this error's details in the LSP Consoles view (by setting the Debug / Trace combo box in verbose):

Eclipse Public License 2.0. See LICENSE file.