MailChimp for WordPress makes it easy to add different sign-up methods for your MailChimp mailing lists to your WordPress site.
The plugin is actively used on over 300.000 sites with over 10.000 actively paying customers. The plugin comes with a free version which lets you create sign-up forms and integrate with various other forms on your WordPress site, ie subscribe the person filling out your form.
The paid version of the plugin, MailChimp for WordPress Pro, comes with the following benefits over the free version.
– AJAX forms, forms do not require a page reload.
– Unlimited number of forms.
– Styles Builder, an easy live-preview tool to style your forms.
– Reports. Each sign-up attempts is logged and visualised in insightful graphs.