Umbraco is the leading open source ASP.NET CMS. You can start using Umbraco in 2 minutes, by taking a free trial of Umbraco Cloud.
We detected the following sites were using Umbraco CMS
A CMS will sometimes include a meta tag within the html of each page. This is usually a "generator" tag like <meta name="generator" content="What CMS" /> but could also be "application-name", "Powered-By" or anyting else the CMS creators decide to use.