Flex Fields

Flex Forms is a modular and flexible form builder plugin for WordPress, designed to be lightweight yet feature-rich. It allows you to quickly build forms with various field types, manage submissions, and integrate with your theme and workflow easily.
Key Features:
<ul>
<li>Easy form creation via WordPress admin</li>
<li>Drag-and-drop field ordering</li>
<li>Email notifications on submission</li>
<li>Submission storage in database</li>
<li>Google reCAPTCHA v2/v3 support</li>
<li>Custom shortcode per form</li>
<li>SMTP email sending support with test email</li>
<li>Force “From” email override (site-wide)</li>
<li>Full integration with <a href="https://flex-fields.com/" rel="nofollow ugc">Flex Fields</a></li>
<li>Developer-friendly hooks and filters</li>
</ul>
<h3>External Services</h3>
Flex Forms may interact with third-party services depending on your configuration:
<h3>Email Sending</h3>
Flex Forms supports custom SMTP configuration for reliable email delivery.
<ul>
<li>What data is sent: Form submission content (user input).</li>
<li>When data is sent: When a user submits a form or when a notification is triggered.</li>
<li>Where data is sent: To the configured email recipient(s) via your selected email service provider.</li>
<li>Privacy & Terms: Email service providers’ policies apply (e.g., SendGrid, Mailgun, custom SMTP).
<ul>
<li>Example terms:</li>
<li>SendGrid: https://sendgrid.com/policies/tos/</li>
<li>Mailgun: https://www.mailgun.com/legal/</li>
</ul>
</li>
</ul>
<h3>Google reCAPTCHA</h3>
Used to prevent spam form submissions.
<ul>
<li>What the service is and what it is used for: 
Verifies that a user is human when submitting a form.</li>
<li>What data is sent and when: 
The user’s IP address and browser information are sent to Google when the user interacts with a reCAPTCHA-enabled form.</li>
<li>Where data is sent: 
Google servers.</li>
<li>Privacy & Terms:
<ul>
<li>https://policies.google.com/terms</li>
<li>https://policies.google.com/privacy</li>
</ul>
</li>
</ul>

Flex Forms

A lightweight yet powerful form builder with database storage, email alerts, reCAPTCHA, SMTP configuration, and deep Flex Fields integration.

tmertz

Designed to make it easier to serve signup form on sites for LARP activities, this plugin aims to be very flexible in the way it handles input form fields.
What makes this plugin awesome is:
<ul>
<li>the ability for you to define the form you need to get the data you want.</li>
<li>the fact that it has been designed with the less is more paradigm in mind.</li>
</ul>
Thank you goes out to nkuttler of the IRC channel for his help sorting out my problems with $_POST.

Osmig Signup Plugin

This is a simple and flexible plugin to handle signups with the form fields you define.

Flex Forms vs Osmig Signup Plugin