VNC client using HTML5 (Web Sockets, Canvas) with encryption (wss://) support.
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noVNC: HTML5 VNC Client


noVNC is a VNC client implemented using HTML5 technologies, specifically Canvas and WebSockets (supports 'wss://' encryption). noVNC is licensed under the LGPLv3.

Special thanks to Sentry Data Systems for sponsoring ongoing development of this project (and for employing me).

Notable commits, announcements and news are posted to @noVNC


Running in Chrome before and after connecting:


See more screenshots here.

Projects/Companies using noVNC

Browser Requirements

  • HTML5 Canvas: Except for Internet Explorer, most browsers have had Canvas support for quite some time. Internet Explorer 9 will have Canvas support (finally).

  • HTML5 WebSockets: For browsers that do not have builtin WebSockets support, the project includes web-socket-js, a WebSockets emulator using Adobe Flash.

  • Fast Javascript Engine: noVNC avoids using new Javascript functionality so it will run on older browsers, but decode and rendering happen in Javascript, so a slow Javascript engine will mean noVNC is painfully slow.

  • I maintain a more detailed list of browser compatibility here.

Server Requirements

Unless you are using a VNC server with support for WebSockets connections (only my fork of libvncserver currently), you need to use a WebSockets to TCP socket proxy. There is a python proxy included ('websockify'). One advantage of using the proxy is that it has builtin support for SSL/TLS encryption (i.e. "wss://").

There a few reasons why a proxy is required:

  1. WebSockets is not a pure socket protocol. There is an initial HTTP like handshake to allow easy hand-off by web servers and allow some origin policy exchange. Also, each WebSockets frame begins with 0 ('\x00') and ends with 255 ('\xff').

  2. Javascript itself does not have the ability to handle pure byte arrays. The python proxy encodes the data as base64 so that the Javascript client can decode the data as an integer array.

Quick Start

  • Use the launch script to start a mini-webserver and the WebSockets proxy (websockify). The --vnc option is used to specify the location of a running VNC server:

    ./utils/ --vnc localhost:5901

  • Point your browser to the cut-and-paste URL that is output by the launch script. Enter a password if the VNC server has one configured. Hit the Connect button and enjoy!

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