DigitalME

This plugin adds a simple WordPress button linking to your Discord server. 
You can set your Discord invite URL once in the Settings page, and use the shortcode anywhere in posts, pages, or blocks.
Features: 
* Shortcode [digitalme_discord_button] to place the button anywhere 
* Global settings page for Discord URL under Settings → Discord Button 
* Fixed text (“Join our Discord!”) and styling 
* Lightweight and fully WP.org compliant

DigitalME Join Button for Discord

A simple shortcode and settings page to display a fixed 'Join our Discord!' button.

rtCamp

Jignesh Nakrani

With this plugin, you can send auto slack invitation via email to user who submitted a gravity form. 
This plugin works with Gravity form only. Once you have created a gravity form and do required settings, this plugin will start working. Whenever new entries are submitted via gravity form, the respective user will receive an email with slack channel invitation link.
<h4>Requirement</h4>
<ol>
<li>Gravity Form plugin.</li>
<li>Slack Team Name.</li>
<li>Slack Authentication Token.</li>
</ol>
<h4>How this plugin works</h4>
<ol>
<li>Set the “Team Name” and slack authentication token under Gravity Form -> Settings -> Slack Invite.</li>
<li>Now, create a gravity form, go to Form Setting -> Slack Invite and click on “Create one” link to set an email field.</li>
<li>Once the user submit a gravity form, he/she will receive a slack invite via email notification.</li>
</ol>
Example: Let say you have a slack team group, in which you want users to come up and chat/discuss. However, you don’t know to whom you want to invite. 
So in this case, just create a gravity form with some fields and make it public on your website. Interested members will submit that form and they will automatically receives invitation email.
Note: Your Gravity Form must have an email field.
Development of this plugin is done on <a href="https://github.com/rtCamp/automate-slack-invite-gravityforms" rel="nofollow ugc">GitHub</a>. You can report issues and suggest features.

Automate Slack Invite Gravityforms

I hate giving bad reviews but this plugin just doesn't work. I've submitted three separate issues on the support forum and still no reply after more than 3 months.

Doesn't work

With this plugin, you can send auto slack invitation via email to user who submitted a gravity form.

DigitalME Join Button for Discord vs Automate Slack Invite Gravityforms