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mumble-web is an HTML5 Mumble client for use in modern browsers.

A live demo is running here (or without WebRTC).

The Mumble protocol uses TCP for control and UDP for voice. Running in a browser, both are unavailable to this client. Instead Websockets are used for control and WebRTC is used for voice (using Websockets as fallback if the server does not support WebRTC).

In WebRTC mode (default) only the Opus codec is supported.

In fallback mode, when WebRTC is not supported by the server, only the Opus and CELT Alpha codecs are supported. This is accomplished with libopus, libcelt (0.7.1) and libsamplerate, compiled to JS via emscripten. Performance is expected to be less reliable (especially on low-end devices) than in WebRTC mode and loading time will be significantly increased.

Quite a few features, most noticeably all administrative functionallity, are still missing.



mumble-web can either be installed directly from npm with npm install -g mumble-web or from git (recommended because the npm version may be out of date):

git clone
cd mumble-web
npm install

Note that npm must not be ran as the root user (even in a container) because it will try to do special things which cause the build to fail, use a non-root user account instead.

The npm version is prebuilt and ready to use whereas the git version allows you to e.g. customize the theme before building it.

Either way you will end up with a dist folder that contains the static page.


At the time of writing this there do not seem to be any Mumble servers which natively support Websockets+WebRTC. Grumble natively supports Websockets and can run mumble-web in fallback mode but not (on its own) in WebRTC mode. To use this client with any standard mumble server in WebRTC mode, mumble-web-proxy must be set up (preferably on the same machine that the Mumble server is running on).

Additionally you will need some web server to serve static files and terminate the secure websocket connection (mumble-web-proxy only supports insecure ones).

Here are two web server configuration files (one for NGINX and one for Caddy server) which will serve the mumble-web interface at and allow the websocket to connect at wss:// (similar to the demo server). Replace <proxybox> with the host name of the machine where mumble-web-proxy is running. If mumble-web-proxy is running on the same machine as your web server, use localhost.

  • NGINX configuration file
server {
        listen 443 ssl;
        ssl_certificate /etc/letsencrypt/live/;
        ssl_certificate_key /etc/letsencrypt/live/;

        location / {
                root /path/to/dist;
        location /demo {
                proxy_pass http://<proxybox>:64737;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection $connection_upgrade;

map $http_upgrade $connection_upgrade {
        default upgrade;
        '' close;
  • Caddy configuration file (Caddyfile) {
} {
  tls "/etc/letsencrypt/live/" "/etc/letsencrypt/live/"
  root /path/to/dist
  proxy /demo http://<proxybox>:64737 {

To run mumble-web-proxy, execute the following command. Replace <mumbleserver> with the host name of your Mumble server (the one you connect to using the normal Mumble client). Note that even if your Mumble server is running on the same machine as your mumble-web-proxy, you should use the external name because (by default, for disabling see its README) mumble-web-proxy will try to verify the certificate provided by the Mumble server and fail if it does not match the given host name.

mumble-web-proxy --listen-ws 64737 --server <mumbleserver>:64738

If your mumble-web-proxy is running behind a NAT or firewall, take note of the respective section in its README.

Make sure that your Mumble server is running. You may now open in a web browser. You will be prompted for server details: choose either address: with port: 443 or address: with port: 443/demo. You may prefill these values by appending ? Choose a username, and click Connect: you should now be able to talk and use the chat.

Here is an example of systemd service, put it in /etc/systemd/system/mumble-web.service and adapt it to your needs:

Description=Mumble web interface
Documentation= mumble-server.service mumble-server.service

ExecStart=/usr/bin/websockify --web=/usr/lib/node_modules/mumble-web/dist --ssl-target localhost:64737 localhost:64738



systemctl daemon-reload
systemctl start mumble-web
systemctl enable mumble-web


The app/config.js file contains default values and descriptions for all configuration options. You can overwrite those by editing the config.local.js file within your dist folder. Make sure to back up and restore the file whenever you update to a new version.


The default theme of mumble-web tries to mimic the excellent MetroMumbleLight theme. mumble-web also includes a dark version, named MetroMumbleDark, which is heavily inspired by MetroMumble's dark version.

To select a theme other than the default one, append a theme=dark query parameter (where dark is the name of the theme) when accessing the mumble-web page. E.g. thisis the live demo linked above but using the dark theme (dark is an alias for MetroMumbleDark).

Custom themes can be created by deriving them from the MetroMumbleLight/Dark themes just like the MetroMumbleDark theme is derived from the MetroMumbleLight theme.

Matrix Widget

mumble-web has specific support for running as a widget in a Matrix room.

While just using the URL to a mumble-web instance in a Custom Widget should work for most cases, making full use of all supported features will require some additional trickery. Also note that audio may not be functioning properly on newer Chrome versions without these extra steps.

This assumes you are using the Riot Web or Desktop client. Other clients will probably require different steps.

  1. Type /devtools into the message box of the room and press Enter
  2. Click on Send Custom Event
  3. Click on Event in the bottom right corner (it should change to State Event)
  4. Enter im.vector.modular.widgets for Event Type
  5. Enter mumble for State Key (this value may be arbitrary but must be unique per room)
  6. For Event Content enter (make sure to replace the example values):
  "waitForIframeLoad": true,
  "name": "Mumble",
  "creatorUserId": "@your_user_id:your_home_server.example",
  "url": "$matrix_display_name&theme=$theme&avatarurl=$matrix_avatar_url",
  "data": {},
  "type": "customwidget",
  "id": "mumble"

The $var parts of the url are intentional and will be replaced by Riot whenever a widget is loaded (i.e. they will be different for every user). The username query parameter sets the default username to the user's Matrix display name, the theme parameter automatically uses the dark theme if it's used in Riot, and the avatarurl will automatically download the user's avatar on Matrix and upload it as the avatar in Mumble. Finally, the matrix=true query parameter replaces the whole Connect to Server dialog with a single Join Conference button, so make sure to remove it if you do not supply default values for all connection parameters as above. The type needs to be jitsi to allow the widget to use audio and to stay open when switching to a different room (this will hopefully change once Riot is able to ask for permission from the user by itself). The id should be the same as the State Key from step 5. See here for more information on the values of these fields. 7. Press Send