XML Language Server (LemMinX)

Build Status

LemMinX is a XML language specific implementation of the Language Server Protocol and can be used with any editor that supports the protocol, to offer good support for the XML Language. The server is based on:


See screenshots in the wiki.

See the changelog for the latest release.


XML Language Server Demo

Get started


To debug the XML LS you can use XMLServerSocketLauncher:

  1. Run the XMLServerSocketLauncher in debug mode (e.g. in eclipse)
  2. Connect your client via socket port. Default port is 5008, but you can change it with start argument --port in step 1

Client connection example using Theia and TypeScript:

let socketPort = '5008'
console.log(`Connecting via port ${socketPort}`)
const socket = new net.Socket()
const serverConnection = createSocketConnection(socket,
    socket, () => {
this.forward(clientConnection, serverConnection)

Maven coordinates:

Here are the Maven coordinates for lemminx (replace the X.Y.Z version with the latest release):

    <!-- classifier:uber includes all dependencies -->

for Gradle:

compile(group: 'org.lemminx', name: 'org.eclipse.lemminx', version: 'X.Y.Z', classifier: 'uber')

You will have to reference the Maven repository hosting the dependency you need. E.g. for Maven, add this repository to your pom.xml or settings.xml :


And if you want to consume the SNAPSHOT builds instead:



Here are some clients consuming this XML Language Server:


The XML Language Server is extensible with plugin kind (with SPI). Additionally to XSD-based validation and assistance, those extensiosn allow to enrich the validation and assistance, typically for specific files or contexts.

Example of extensions include: