A basic JsonSchemaGenerator

JsonSchemaGenerator.cs

public class JsonSchemaGenerator
{
    public JsonSchema GenerateSchema(Type type)
    {
        if (type == typeof(string))
        {
            return new JsonSchema { Type = "string" };
        }
        else if (type == typeof(int) || type == typeof(decimal) || type == typeof(double))
        {
            return new JsonSchema { Type = "number" };
        }
        else if (type == typeof(bool))
        {
            return new JsonSchema { Type = "boolean" };
        }
        else if (type == typeof(DateTime))
        {
            return new JsonSchema { Type = "string", Format = "date-time" };
        }
        else if (type.IsArray)
        {
            var elementType = type.GetElementType();
            var arraySchema = GenerateSchema(elementType);
            return new JsonSchema { Type = "array", Items = arraySchema };
        }
        else if (type.IsClass)
        {
            var properties = type.GetProperties();
            var objectSchema = new JsonSchema { Type = "object", Properties = new Dictionary<string, JsonSchema>() };

            foreach (var property in properties)
            {
                var propertySchema = GenerateSchema(property.PropertyType);
                objectSchema.Properties.Add(property.Name, propertySchema);
            }

            return objectSchema;
        }

        throw new NotSupportedException($"Type '{type.Name}' is not supported.");
    }
}

public class JsonSchema
{
    public string Type { get; set; }
    public string Format { get; set; }
    public JsonSchema Items { get; set; }
    public Dictionary<string, JsonSchema> Properties { get; set; }
}