Meitar

Add one or more “lists” to any post. Registered users of your site can then join or leave the list. Lists can be used for any purpose (event RSVPs, running polls or surveys, etc.) and can be unobtrusively added to any post type. Optionally, lists can have a maximum number of users on it that you define, after which any user who joins the list is automatically added to an overflow “waitlist.”
This plugin also serves the needs of plugin developers who are looking for a simple way to manage sets of users on a per-post basis. A simple set of public functions are exposed to other installed plugins that developers can use to get information about the lists themselves, and the users listed on them.
<h4>Code examples</h4>
After installing and activating this plugin, include it in your own plugin project as follows:
<pre><code><?php
/**
 * Plugin Name: My plugin project
 * Plugin URI: http://example.com/
 * Description: Example plugin for playing with WP-Waitlist.
 * Author: Me, myself, and I
 * Version: 1.0
 */

class My_Plugin {
 private $WP_Waitlist;

 public function __construct () {
 add_action('init', array($this, 'registerDepdencies'));
 }

 public function registerDepdencies () {
 global $WP_Waitlist;
 if (!$WP_Waitlist) {
 // WP-Waitlist is not available, issue an error.
 } else {
 $this->$WP_Waitlist = $WP_Waitlist;
 }
 }

}

$My_Plugin = new My_Plugin();
</code></pre>
At that point, you can call WP-Waitlist’s functions in your own plugin as follows:
<pre><code>public function myPluginLearnsAboutWaitlists ($post_id) {
 // Get an array of all lists that the author of this post created.
 $lists = $this->WP_Waitlist->getListsForPost($post_id);

 // You can iterate through the lists attached to this post.
 foreach ($lists as $list_name) {
 $list_properties = $this->WP_Waitlist->getListProperties($post_id, $list_name);
 foreach ($list_properties as $property_name => $property_value) {
 print "$property_name is $property_value ";
 }

 // You can also learn which users are on the list...
 $user_ids = $this->WP_Waitlist->getListedUsers($post_id, $list_name);
 foreach ($user_ids as $id) {
 $this_wp_user = get_userdata($id); // $this_wp_user is now a WP_User object.
 }

 // ...and which users have been waitlisted (joined after the list reached capacity).
 $waitlisted_users = $this->WP_Waitlist->getWaitlistedUsers($post_id, $list_name);

 // You can also get an array all users who have added themselves to the list, sorted by date.
 $all_user_ids_on_list = $this->WP_Waitlist->getUsersOnList($post_id, $list_name);
 }

}
</code></pre>
<h4>Plugins that use this one</h4>
Know of a plugin that’s using WP-Waitlist? Let us know by posting in <a href="https://wordpress.org/support/plugin/wp-waitlist/" rel="ugc">the support forum</a>. 🙂
<ul>
<li><a href="https://wordpress.org/plugins/volunteer-project-manager/" rel="ugc">WordPress Volunteer Project Manager</a> 
Maintaining this plugin is a labor of love. However, if you like it, please consider <a href="https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=meitarm%40gmail%2ecom&lc=US&item_name=Waitlists%20for%20WordPress&item_number=wp%2dwaitlists&currency_code=USD&bn=PP%2dDonationsBF%3abtn_donateCC_LG%2egif%3aNonHosted" rel="nofollow ugc">making a donation</a> for your use of the plugin, <a href="http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Fs%3Fie%3DUTF8%26redirect%3Dtrue%26sort%3Drelevancerank%26search-type%3Dss%26index%3Dbooks%26ref%3Dntt%255Fathr%255Fdp%255Fsr%255F2%26field-author%3DMeitar%2520Moscovitz&tag=maymaydotnet-20&linkCode=ur2&camp=1789&creative=390957" rel="nofollow ugc">purchasing one of Meitar’s web development books</a> or, better yet, contributing directly to <a href="http://Cyberbusking.org/" rel="nofollow ugc">Meitar’s Cyberbusking fund</a>. (Publishing royalties ain’t exactly the lucrative income it used to be, y’know?) Your support is appreciated!</li>
</ul>

WP-Waitlist

Waitlists for WordPress lets you create and manage user lists of almost any type in any post.

Mauricio Galetto

This plugin allows users to create lists of different types (simple, numbered, cart and poll) and share them. 
The items of these lists are the posts of the types to configure (Ex: post, page, product, other CPT, etc). 
Create classic lists like Favorites, Bookmarks, Wish List. Or poll lists like “Which one should I buy?”, or shopping cart lists of every month, etc. 
It is flexible and extensible. 
The plugin adds custom endpoints to the wordpress REST API and includes a client that will display operations on user lists in a modal.
<h3>Default lists types</h3>
The plugin comes with 6 types of lists: 
* Simple: Simple list sorted according to their items added. 
* Numbered: List with your numbered items. You can edit the order in which the items will be displayed. 
* Poll: You can ask others for their opinion. 
* Shopping Cart: List to add items to a virtual cart ( only on Woocommerce ). 
* Favorites This type of list conceptually always exists for users, that is, the user does not create them but simply adds items. 
* Bookmarks Equivalent to favorites.
All list types can be disabled.
If you are a developer, and you are making a theme you can register your own list types.
<h3>Features</h3>
<ul>
<li>Roles that can create lists is configurable (for each type of list).</li>
<li>Post type that can be added to lists is configurable (per list type).</li>
<li>Title and description of the lists can be editable (configurable in each type of list)</li>
<li>List items can be saved with a comment (configurable in each type of list)</li>
<li>The lists can be private or public (configurable options in each type of list)</li>
<li>Max items per list (configurable in each type of list)</li>
<li>Share buttons for public lists</li>
</ul>
<h3>Collections Archive</h3>
The plugin adds a new page to the site where all the collections of the users are shown. This page can be disabled/enabled on the plugin settings. 
This page is also used as the basis for displaying each list, but disabling the archive page from the plugin settings does not disable the pages of each collection.. 
Archive URL example: https://domain.com/user-post-collection/ 
Collection URL example: https://domain.com/user-post-collection/list-x-by-tauri/
<h3>Shortcode</h3>
You can use the shortcode [user_posts_collections] to show the lists. Example:
<pre><code>[user_posts_collections type="vote" tpl-items="cards" exclude="32,45"]
[user_posts_collections author="23" tpl-items="list"]
[user_posts_collections limit="5" pagination="1" tpl-cols="4,4,4,3,2,1"]
[user_posts_collections author-name="tauri" orderby="title" order="ASC" limit=10 pagination=1]
[user_posts_collections include="23,31,412"]
</code></pre>
<h4>Shortcode options</h4>
<ul>
<li>type: simple|numbered|vote|favorites|bookmarks|cart</li>
<li>author-name: Author username</li>
<li>author: Author ID</li>
<li>include: Lists ID to include (comma separated)</li>
<li>exclude: Lists ID to exclude (comma separated)</li>
<li>orderby: ID|views|vote_counter|count|created|modified|title</li>
<li>order: ASC|DESC</li>
<li>limit: Max lists to show</li>
<li>pagination: Show pagination. Set to 1 for enabled. Default: 0</li>
<li>id: Set unique string. Only letters, numbers and “-“. Used for pagination.</li>
<li>tpl-items: (card|list) List type</li>
<li>tpl-cols: Number of columns, comma separated: xxl,xl,lg,md,sm,xs (for card list type) Default: 4,4,4,3,2,1</li>
<li>tpl-cols-(xs|sm|md|lg|xl|xxl): (1|2|3|4|5) Number of columns (for card list type)</li>
<li>tpl-thumbs: Default thumbnails layout. Set to “off” to not show</li>
<li>tpl-thumbs-(xs|sm|md|lg|xl|xxl): (0|2×2|2×3|3×2|4×1|[1-4]x[1-4]) Thumbnails layout</li>
<li>tpl-desc: (on|off) Show description. Set to “off” to hide description</li>
<li>tpl-user: (on|off) Show author. Set to “off” to hide user</li>
<li>tpl-meta: (on|off) Show meta. Set to “off” to hide meta</li>
</ul>

User Post Collections


I hope the developer can continue updating this as needed. I accidentally found this today and it's fantastic!


Currently, the best bookmarking/list saving free plugin

Create & share lists with post types like posts, pages, products, etc. Build classic lists (Favorites, Bookmarks) and polls and cart lists and more.

WP-Waitlist vs User Post Collections