DotVVM

<div class="form-group">
    <dot:TextBox Text="{value: Number}" />

    <dot:Button Text="Increment"
                Click="{command: Increment()}" />
</div>

public class IncViewModel 
{
  public int Number { get; set; }

  public void Increment() 
  {
    Number++;
  }
}

<dot:Button Text="Increment"
            Click="{command: Increment()}"
            class="btn btn-default" />

<dot:ComboBox DataSource="{value: Category}" 
    SelectedValue="{value: SelectedCategory}" />

<dot:TextBox Text="{value: OtherCategory}" 
    Enabled="{value: Category == "Other"}" />

[Required]
[EmailAddress]
public string CustomerEmail { get; set; }

<div Validator.InvalidCssClass="has-error" 
     Validator.Value="{value: FirstName}">
  <dot:TextBox Text="{value: FirstName}" />
</div>

<dot:ValidationSummary 
    class="alert alert-danger" />