If you wish to validate specific content such as RSS/Atom feeds or CSS stylesheets, Mobile OK content, or to find broken links, there are other validators and tools available.
As an alternative you can also try our non-DTD-based validator.
NET Core Web API Attributes Functional Programming (F#) for C# Developers Xamarin. NET Standard 2.0 and XAML Standard Using MVVM in your Xamarin.
This validator checks the markup validity of Web documents in HTML, XHTML, SMIL, Math ML, etc.
This can be performed with some basic Java Script commands.