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Monaco Language Client, VSCode WebSocket Json RPC, Monaco Editor React and examples

Github Pages monaco-languageclient PRs Welcome
monaco-languageclient Version monaco-languageclient Downloads vscode-ws-jsonrpc Version vscode-ws-jsonrpc Downloads monaco-editor-react Version monaco-editor-react Downloads

This repository now host multiple npm packages under one roof:

The examples not requiring a backend are now available via GitHub Pages.

Official Documentation

Since monaco-languageclient version 10 we started to build an official documentation. This will be continuously extended.

Migration Guide

We added a migration guide with the release of monaco-languageclient version 10.

Changelogs, current versions and compatibility table

CHANGELOGs for each project are available from the linked location:

  • CHANGELOG for monaco-languageclient is found here
  • CHANGELOG for vscode-ws-jsonrpc is found here
  • CHANGELOG for @typefox/monaco-editor-react is found here
  • CHANGELOG for monaco-languageclient-examples is found here

Important Project changes and notes about the project's history are found here.

These are the current versions of packages from this repository and their alignment with @codingame/monaco-vscode-api monaco-editor and vscode:

  • monaco-languageclient: 10.0.0 (release date: unreleased)
  • @typefox/monaco-editor-react: 7.0.0 (release date: unreleased)
  • Aligned with:
    • @codingame/monaco-vscode-[editor]-api: ^21.1.0
    • vscode: 1.104.1
    • monaco-editor: 0.53.0
  • vscode-ws-jsonrpc: 3.5.0 (release date: 2025-08-11)

Check find the full compatibility table with all previous versions.

Getting started

On your local machine you can prepare your dev environment as follows. At first it is advised to build everything. Locally, from a terminal do:

git clone https://github.com/TypeFox/monaco-languageclient.git
cd monaco-languageclient
npm i
# Cleans-up, compiles and builds everything
npm run build

Vite dev server

Start the Vite dev server. It serves all client code at localhost. You can go to the index.html and navigate to all client examples from there. You can edit the client example code directly (TypeScript) and Vite ensures it automatically made available:

npm run dev
# OR: this clears the cache and has debug output
npm run dev:debug

As this is a npm workspace the main package.json contains script entries applicable to the whole workspace like watch, build and lint, but it also contains shortcuts for launching scripts from the childe packages like npm run build:examples.

If you want to change the libries and see this reflected directly, then you need to run the watch command that compiles all TypeScript files form both libraries and the examples:

npm run watch

Usage

Please look at the respective section in the packages:

  • Usage for monaco-languageclient is found here
  • Usage for vscode-ws-jsonrpc is found here
  • Usage for @typefox/monaco-editor-react is found here

Examples Overview

The examples demonstrate mutliple things:

  • How monaco-languageclient is use by monaco-edtior-wrapper or @typefox/monaco-editor-react to have an editor that is connected to a language server either running in the browser in a web worker or vscode-ws-jsonrpc. is used to an external process via web-socket.
  • How different language servers can be intergrated in a common way, so they can communicate via web-socket to the front-end running in the browser.

Main Examples

JSON Language client and language server example (Location)

The json-server runs an external Node.js Express app where web sockets are used to enable communication between the language server process and the client web application (see JSON Language Server). The json-client using extended mode as editor app which connects to the language server and therefore requires the node server app to be run in parallel. The json-client using classic mode as editor app which connects to the language server and therefore requires the node server app to be run in parallel.

Python Language client and pyright language server example (Location)

The python-server runs an external Node.js Express app where web sockets are used to enable communication between the language server process and the client web application (see Pyright Language Server). The python-client contains the editor app which connects to the language server and therefore requires the node server app to be run in parallel. It is also possible to use a @typefox/monaco-editor-react app to connect to the server. Both versions now feature a debugger, see here.

Groovy Language client and language server example (Location)

The groovy-server runs an external Java app where web sockets are used to enable communication between the language server process and the client web application (Groovy Language Server). The groovy-client contains the editor app which connects to the language server and therefore requires the node server app to be run in parallel.

Java Language client and language server example (Location)

The java-server runs an external Java app where web sockets are used to enable communication between the language server process and the client web application (Java Language Server). The java-client contains the editor app which connects to the language server and therefore requires the node server app to be run in parallel.

Langium examples (here client and server communicate via vscode-languageserver-protocol/browser instead of a web socket used in the three examples above

Cpp / Clangd (Location)

It contains both the language client and the langauge server (web worker). The clangd language server is compiled to wasm so it can be executed in the browser. Heads up: This is a prototype and still evolving.

Application Playground (Location)

This example uses the view service provider from @codingame/monaco-vscode-editor-api to build an application that utilizes more vscode features. Heads up: This is a prototype and still evolving.

Langium grammar DSL (Location)

It contains both the language client and the langauge server (web worker). Here you can chose beforehand if the wrapper should be started in classic or extended mode.

Statemachine DSL (created with Langium) (Location)

It contains both the language client and the langauge server (web worker). It is also possible to use a @typefox/monaco-editor-react app to connect to the server.

Browser example (Location)

This demonstrates how an editor app can be combined with a language service written in JavaScript. This example can now be considered legacy as the web worker option eases client side language server implementation and separation, but it still shows a valid way to achieve the desired outcome.

Purely monaco-editor related examples

See Typescript Language support.

Server processes

JSON Language Server

For the json-client, react-client or the client-webpack examples you need to ensure the json-server example is running:

# start the express server with the language server running in the same process.
npm run start:example:server:json
Pyright Language Server

For the python-client example you need to ensure the python-server example is running:

# start the express server with the language server running as external node process.
npm run start:example:server:python
Graalpy Debugger

If you want to use the debugger in the python-client example you need to the debugger is running. You require docker-compose to run it. From the project root run docker-compose -f ./packages/examples/resources/debugger/docker-compose.yml up -d. First start up will take longer as the container is downloaded from GitHub's container registry. Use docker-compose -f ./packages/examples/resources/debugger/docker-compose.yml down to stop it.

Groovy Language Server

For the groovy-client example you need to ensure the groovy-server example is running. You require docker-compose which does not require any manual setup (OpenJDK / Gradle). From the project root run docker-compose -f ./packages/examples/resources/groovy/docker-compose.yml up -d. First start up will take longer as the container is downloaded from GitHub's container registry. Use docker-compose -f ./packages/examples/resources/groovy/docker-compose.yml down to stop it.

Java Language Server

For the java-client example you need to ensure the java-server example is running. You require docker-compose which does not require any manual setup (OpenJDK / Eclipse JDT LS). From the project root run docker-compose -f ./packages/examples/resources/eclipse.jdt.ls/docker-compose.yml up -d. First start up will take longer as the container is downloaded from GitHub's container registry. Use docker-compose -f ./packages/examples/resources/eclipse.jdt.ls/docker-compose.yml down to stop it.

Verification Examples & Usage

None of the verification examples is part of the npm workspace. Some bring substantial amount of npm dependencies that pollute the main node_modules dependencies and therefore these examples need to be build and started independently. All verifaction examples re-uses the code form the json client example and therefore require the json server to be started.

VSCode integration

You can as well run vscode tasks to start and debug the server in different modes and the client.

Featured projects

Troubleshooting

For troubleshooting, please also see the Troubleshooting Guide.

Licenses

  • monaco-languageclient: MIT
  • vscode-ws-jsonrpc: MIT
  • @typefox/monaco-editor-react: MIT
  • monaco-languageclient-examples: MIT