KasmVNC — Modern Web-Native VNC Server

Introduction

KasmVNC is a modern fork of TigerVNC rebuilt for web-native remote desktop access. It replaces traditional VNC viewers with a performant HTML5 client, adds multi-user isolation, and includes hardware video encoding — making it the foundation for Kasm Workspaces and other browser-based desktop solutions.

What KasmVNC Does

• Serves a full Linux desktop or application through a web browser via WebSocket
• Encodes the display using WebP, JPEG, and hardware H.264 for low bandwidth consumption
• Supports multiple simultaneous users with isolated sessions on a single server
• Provides clipboard sync, file transfer, and audio streaming to the browser
• Includes built-in TLS encryption and token-based authentication

Architecture Overview

KasmVNC runs as an X11 VNC server that captures the framebuffer, encodes changed regions using adaptive quality algorithms, and streams them to a built-in web server over WebSocket. The HTML5 client (based on noVNC with significant modifications) renders frames in a canvas element. Hardware encoding leverages VA-API or NVENC when available. Each user session runs in a separate X server instance for isolation.

Self-Hosting & Configuration

• Install from .deb or .rpm packages available on GitHub releases
• Start a session with vncserver :1 and access via https://host:6901
• Configure resolution, frame rate, and encoding quality in ~/.vnc/kasmvnc.yaml
• Enable hardware encoding by installing VA-API or NVIDIA drivers
• Deploy in Docker with Kasm Workspaces images for containerized desktop environments

Key Features

• No VNC client required — access full desktops from any modern browser
• Adaptive encoding selects WebP, JPEG, or H.264 based on content and bandwidth
• Multi-user session isolation on a single host
• Built-in file upload/download and bidirectional clipboard
• DRI3 GPU rendering support for 3D-accelerated applications in the browser

Comparison with Similar Tools

• TigerVNC — Traditional VNC server; requires a native VNC viewer, no built-in web client
• noVNC — Web-based VNC client that connects to any VNC server; KasmVNC includes a modified noVNC plus a purpose-built server
• Apache Guacamole — Clientless remote desktop gateway for VNC/RDP/SSH; adds a middleware layer rather than replacing the VNC server
• Neko — Docker-based virtual browser with WebRTC; focused on single-app sharing rather than full desktop sessions
• XRDP — RDP server for Linux; uses the RDP protocol instead of VNC, requires an RDP client or web gateway

FAQ

Q: How does KasmVNC differ from TigerVNC? A: KasmVNC adds a built-in web client, WebP/H.264 encoding, multi-user isolation, clipboard/file transfer, and drops legacy VNC viewer support.

Q: Can I use KasmVNC without Kasm Workspaces? A: Yes. KasmVNC is a standalone VNC server. Kasm Workspaces is a separate product that orchestrates containerized KasmVNC sessions.

Q: Does it support audio? A: Yes. PulseAudio is captured and streamed to the browser as Opus audio alongside the video feed.

Q: What GPU hardware acceleration is supported? A: VA-API (Intel/AMD) and NVENC (NVIDIA) for video encoding, plus DRI3 for GPU-rendered desktops.

Sources

• https://github.com/kasmtech/KasmVNC
• https://kasmweb.com/kasmvnc