Best approach to make form Widget. Are there any other ways than doing this Iframe approach?

Hi;

I want to make a product where my clients can log in, build simple forms (max 5 fields), grab the code for the form and add to their websites. Basically simple form widgets.

In the past, I did it with simalr approach JS like this

<div id = "form_to_add"> <script type="text/javascript" src="https://timers.site.com/form_to_add/bc.php" data-id="1132" data-lt="broadcast"></script></div> 

And this is the JS that loads the iframe

(function(window)
    { 
         
            var currentScript = document.currentScript; 
            var apiUrl = currentScript.src; 

            if (!('jQuery' in window))
                { 
                    loadJQuery(initialize); 
                }
            else 
                { 
                    initialize(); 
                } 
            function loadJQuery(cb)
                { 
                    var script = document.createElement('script'); 
                    script.src = 'https://code.jquery.com/jquery-3.3.1.min.js'; 
                    script.type = 'text/javascript'; 
                    script.addEventListener('load', cb); 
                    document.getElementsByTagName('head')[0].appendChild(script); 
                } 
            function initialize()
                { 
                    //Validate 
                    var $currentScript = $(currentScript); 
                    var params = $.param({ 
                        action: 'load-template' 
                        , launch_owner_email_hashed: $currentScript.data('launch_owner_email_hashed') 
                        , launch_id: $currentScript.data('launch_id') 
                    }); 

                    $.get(apiUrl, params).then(function(html){ 
                        var div = $('<div>').html(html); 
                        $currentScript.after(div); 
                    });

                }


    }
(this));

I wanna take some ideas before starting. What do you recommend as simple, fast and good option? Are there any other ways than doing this Iframe approach?

Thanks