wprecaptcha

WP reCAPTCHA protects your site from spam and abuse. It uses advanced risk analysis techniques to tell humans and bots apart.
WP recaptcha is the only WP Plugin curretly offering reCAPTCHA v3 for Gravity Forms.
WP recaptcha Supports all Google reCAPTCHA versions: 
* Version 3 
* Version 2 – checkbox 
* Version 2 – invisible
WP recaptcha is very simple to use! just select the page that contains the form – WP recaptcha will automatically generate the required recaptcha code.
<a href="https://demo.wprecaptcha.com/" rel="nofollow ugc">View Demo</a>
<h4>Free Features</h4>
<ul>
<li>Add Google reCAPTCHA to:
<ul>
<li>Login Form</li>
<li>Register Form</li>
<li>Lost Password Form</li>
<li>Reset Password Form</li>
<li>Comments Form</li>
</ul>
</li>
<li>Disable Google reCAPTCHA for registered users</li>
<li>Select Google reCAPTCHA language manually or Switch Languages Automatically.</li>
<li>Supports Google reCAPTCHA:
<ul>
<li>Version 3</li>
<li>Version 2 – checkbox</li>
<li>Version 2 – invisible</li>
</ul>
</li>
<li>Available Google reCAPTCHA extended settings for:
<ul>
<li>Version 3
<ul>
<li>Hide badge for Desktop devices</li>
<li>Hide badge for Mobile devices</li>
</ul>
</li>
<li>Version 2 – checkbox
<ul>
<li>Select theme
<ul>
<li>Light</li>
<li>Dark</li>
</ul>
</li>
<li>Select Size
<ul>
<li>Normal</li>
<li>Compact</li>
</ul>
</li>
</ul>
</li>
<li>Version 2 – invisible
<ul>
<li>Select Google badge position:
<ul>
<li>Bottom Right</li>
<li>Bottom Left</li>
<li>Inline</li>
</ul>
</li>
<li>Hide badge for Desktop devices</li>
<li>Hide badge for Mobile devices</li>
</ul>
</li>
</ul>
</li>
<li>Compatible with latest WordPress version</li>
<li>Configure all subsites on the network</li>
</ul>
<blockquote>
Pro Features
All features from Free version included plus: 
 * Compatible with: 
 * Gravity Forms 
 * Contact Form 7 
 * Jetpack Contact Form 
 * Contact Form by WPForms 
 * MailChimp for WordPress 
 * Compatible with Woocommerce: 
 * Login Form 
 * Register Form 
 * Lost Password Form 
 * Order Form 
 * IndividualSettings for each form use Shortcode Generator 
 * 24x7x365 support
</blockquote>
<a href="https://www.wprecaptcha.com/" rel="nofollow ugc">Upgrade to Pro</a>

WP reCaptcha

Add Google reCaptcha to WordPress forms. Easy to add, advanced security for your forms.

Faisal Alvi

This is a simple plugin to generate a contact form using a shortcode.
<h4>The main feature are:</h4>
<ul>
<li> Google Re Captcha.</li>
<li> Can add All data from back end like: To Email, Email subject, Thank you Page, etc.</li>
<li> AJAX is included so form will be fade out and display Thank you message without page load only if ‘Thank you Page’ id is not selected .</li>
<li> If To Email id not selected in settings so data will be sent to admin email automatically.</li>
</ul>
Following fields are included (we will give access to add/update/delete fields in our next update soon):
<ul>
<li>First Name</li>
<li>Last Name</li>
<li>Email Address</li>
<li>Phone</li>
<li>Message</li>
<li>Google Captcha</li>
</ul>
<h4>How to use Shortcode:</h4>
Just use : [cfa_contact_form] 
This will use AJAX and data will be sent to admin email id. (Remember to add captcha keys in settings.)
<h4>Remember:</h4>
You must have to add Google Re Captcha keys. Please go to Settings > CFA.
<ul>
<li>site key</li>
<li>secret key</li>
</ul>
To create your website keys go to: https://www.google.com/recaptcha/intro/index.html.

Contact Form with Ajax

Easy to use

Create your form using a shortcode with the Google Captcha! Shortcode: [cfa_contact_form]

WP reCaptcha vs Contact Form with Ajax