This is a testbed for the Go language's HTML template package which aims to be robust against XSS.
You can enter a template in the box labeled "Template" (see link for syntax) and a JSON data value to evaluate the template with. The template is assumed to be trusted, and the data value is assumed to be malicious. An exploit occurs whenever a template that a naive but trusted author is likely to write suffers an XSS when rendered with any data value.
Please report issues via the Go lang issue tracker, to firstname.lastname@example.org or golang-nuts.