This is a simple Slack public invitation plugin for Craft CMS.
{% set success = craft.session.getFlash('slacksuccess', false) %}
{% if success or craft.request.getQuery('success') %}
<p>Signed up!</p>
{% else %}
<form method="post" accept-charset="UTF-8">
{{ getCsrfInput() }}
<input type="hidden" name="action" value="slackInvite/sendInvite">
<div>
<input type="text" name="name" value="{{ slack is defined ? slack.name }}" placeholder="Name">
<input type="email" name="email" value="{{ slack is defined ? slack.email }}" placeholder="Email">
<input class="submit" type="submit" value="Request an invite">
</div>
{% if slack is defined and slack.hasErrors() %}
<div>
<p>{{ slack.getAllErrors()|join('<br>')|raw }}</p>
</div>
{% endif %}
</form>
{% endif %}