Kit for building HTML-applications. Based on webkit2gtk. No Node.js, etc. No server. Just one Javascript function passes data to the application and returns a response. ( var resp = jsCoreRequest(queryWithParam, data); ) 67 Kb!
Cgi-like plugins. Make your applications and plugins! Besides с++ you can use Python, Perl! I suppose other languages too. Examples included.
Network requests are blocked for security. You can make plugin for this.

0.0.2 - Allowed "data:..." requests. Disable cache. Request format changed. Query parameters are separated from data. Enabled write javascript console messages to stdout.
0.0.5 - Debug info removed. Added TiddlyWiki example.
0.0.7 - File location changed. This allows use one set for different HTML projects. jsCoreMessage deleted. Another way of handling the close event is used.
0.1.1 - Does not work without web extension. Installs files to /usr/local/bin/, /usr/local/share/mdwkit/

You can check files for viruses on virustotal.com.