How to configure Swashbuckle to ignore property on model

Solution for .NET Core 3.1 and .NET Standard 2.1:

Use JsonIgnore from System.Text.Json.Serialization namespace.

( JsonIgnore from Newtonsoft.Json will NOT work )

public class Test
{
    [System.Text.Json.Serialization.JsonIgnore]
    public int HiddenProperty { get; set; }
    public int VisibleProperty { get; set; }
}

If you need to do this but without using JsonIgnore (maybe you still need to serialize/deserialize the property) then just create a custom attribute.

[AttributeUsage(AttributeTargets.Property)]
public class SwaggerExcludeAttribute : Attribute
{
}

Then a schema filter similar to Johng's

public class SwaggerExcludeFilter : ISchemaFilter
{
    #region ISchemaFilter Members

    public void Apply(Schema schema, SchemaRegistry schemaRegistry, Type type)
    {
        if (schema?.properties == null || type == null)
            return;

        var excludedProperties = type.GetProperties()
                                     .Where(t => 
                                            t.GetCustomAttribute<SwaggerExcludeAttribute>() 
                                            != null);

        foreach (var excludedProperty in excludedProperties)
        {
            if (schema.properties.ContainsKey(excludedProperty.Name))
                schema.properties.Remove(excludedProperty.Name);
        }
    }

    #endregion
}

Don't forget to register the filter

c.SchemaFilter<SwaggerExcludeFilter>();

If you mark field/property as internal or protected or private, it will be ignored automatically by swashbuckle in swagger documentation.

Update: Obviously, those properties/fields won't be populated in request/response.