mmattax

noahwesley

jeremyformstack

brianFormstack

Formstack’s <a href="https://www.formstack.com/integrations/wordpress?utm_source=wordpress.com&utm_medium=referral&utm_campaign=integrations" rel="nofollow ugc">WordPress form plugin</a> makes it quick and easy to embed contact forms, lead generation forms, payment forms, and more on your WordPress blogs and websites. Build customized online forms in seconds with our <a href="https://www.formstack.com/features/drag-and-drop?utm_source=wordpress.com&utm_medium=referral&utm_campaign=integrations" rel="nofollow ugc">drag-and-drop interface</a>, and integrate with <a href="https://www.formstack.com/integrations?utm_source=wordpress.com&utm_medium=referral&utm_campaign=integrations" rel="nofollow ugc">40+ third-party apps</a>, including Salesforce, MailChimp, and PayPal.
This plugin features two components:
<ul>
<li>Formstack Widget</li>
<li>Formstack Plugin</li>
</ul>
The Formstack widget allows you to embed Formstack web forms into your sidebar. The widget automatically optimizes the web form’s CSS to make your online forms fit and look great on your WordPress pages.
The Formstack Plugin adds a button to the TinyMCE editor that allows you to easily select the Formstack web form you wish to embed. Once a form is selected, a shortcode will be inserted into the editor, which will be converted to the selected form once your page or blog post is rendered.
This plugin supports the following shortcodes <code>[Formstack]</code>, <code>[formstack]</code>, and <code>[fs]</code>.
A Formstack account and API key are required. <a href="https://www.formstack.com/pricing?source=wp-plugin_utm_medium=pluginlisting" title="Free Online Forms" rel="nofollow ugc">Signup for free today!</a>

Formstack Online Forms

I'm not sure wrapping if this is just this version or all versions, but wrapping your site in an iframe doesn't constitute as a functioning plugin. 
Doesn't work on WP 4.5 as far as i'm concerned.



This doesn't work at all

This plugin allows you to easily embed Web forms built with Formstack's online form builder into your sidebar, pages, and posts.

Jotform

Feedback buttons are great to get feedback from your website visitors. Since it is easy to send a message to you without leaving the page they will improve the quality and the quantity of the feedback you receive from your visitors.
Feedback button plugin is powered by Jotform. Jotform is the first web based WYSIWYG form builder. Its intuitive drag and drop user interface makes form building a breeze. Using Jotform, you can create forms, integrate them to your site and receive responses by email.
Get feedback from your visitors using Jotform Feedback Button. If you are not aware of the problems on your website you can’t fix them. Feedback button is a great way to help you improve your website.
<h3>External Services</h3>
This plugin connects to external services to provide functionality and improve user experience. Below are the details of the external services used:
Jotform Feedback Button 
 – <a href="https://www.jotform.com/privacy/?utm_source=wordpress&utm_medium=plugin_directory&utm_campaign=feedback_button_plugin_content&utm_content=privacy" rel="nofollow ugc">Privacy Policy</a> 
 – <a href="https://www.jotform.com/terms/?utm_source=wordpress&utm_medium=plugin_directory&utm_campaign=feedback_button_plugin_content&utm_content=terms" rel="nofollow ugc">Terms of Use</a>
Service usage 
– The plugin makes external requests on the following domain to render feedback form functionalities: 
 https://www.jotform.com 
– The plugin uses the domain [https://www.jotform.com] as a service to deliver and render the feedback form.
Asset usage 
– The plugin makes external asset requests on the following domain to enable feedback button functionalities: 
 https://js.jotform.com 
– The plugin uses the domain [https://js.jotform.com] as a asset service to deliver and render the embedded feedback button.

Feedback Button – Jotform

Display a beautiful feedback button on the side of your blog. When a reader clicks on it a feedback form pops up. Completely customizable.

Formstack Online Forms vs Feedback Button – Jotform