noVNC

"noVNC is a HTML5 VNC client that runs well in any modern browser including mobile browsers (iOS and Android).

Features

• Supports all modern browsers including mobile (iOS, Android)
• Supported VNC encodings: raw, copyrect, rre, hextile, tight, tightPNG
• WebSocket SSL/TLS encryption (i.e. "wss://") support
• 24-bit true color and 8 bit colour mapped
• Supports desktop resize notification/pseudo-encoding
• Local or remote cursor
• Clipboard copy/paste
• Clipping or scolling modes for large remote screens
• Easy site integration and theming (3 example themes included)
• Licensed under the MPL 2.0

Browser Requirements

• Chrome 8, Firefox 4, Safari 6, Opera 12, IE 11, Edge 12, etc.
  
• HTML5 Canvas, WebSockets and Typed Arrays
  
• Fast Javascript Engine: this is not strictly a requirement, but without a fast Javascript engine, noVNC might be painfully slow.
  
• See the more detailed browser compatibility wiki page.
  

Server Requirements
Unless you are using a VNC server with support for WebSockets connections (such as x11vnc/libvncserver, QEMU, or MobileVNC), you need to use a WebSockets to TCP socket proxy. There is a python proxy included ('websockify')."

https://github.com/novnc/noVNC