# Plugin Dev - Load third party library

What is the preferred way of loading a third party library in a plugin? I'm trying to develop a plugin to extend SproutForms so that users get signed up to Campaign Monitor.

So far I've got an interface in the CP where users can provide their API keys and List ID's into the database, so now I just need to actually add the CM API library.

I know I can just require it, but I was wondering if there is a better way of doing this? Also where would I store the library, just in pluginname/lib/?

I second Brad on this, if there is a composer package, use that.

Whether you use a composer package or a library not found on packagist.org you'll still need to load it so that your plugin can make use of it.

Generally speaking, there are plenty of places where you can import/require third party libraries from but my recommendation would be to do so from the init() method in your main plugin class. As far as where to put it, I would go with one of these 5 acceptable directory names used most often in no particular order library, common, third, lib, or src. I'll use library in the following example.

plugin
PluginClass.php
controllers
templates
...
library
campaignmonitor
OR
library
vendor
composer
campaignmonitor
...


Given the outlined directory structure above, your init() method might look something like this...

// PluginClass.php
public function init()
{
require_once './library/campaignmonitor/SomeClass.php';
require_once './library/campaignmonitor/SomeOtherClass.php';
...
// If using composer

I'd also like to point out that Craft::import() can theoretically import using glob as in Craft::import('plugins.pluginname.library.*) which is cool because those don't get required right away but lazy loaded when needed. However, this only works for class in the Craft namespace so you'll have to stick to a method described above: )
Ideally the third party library would be available as a composer package (you can check on http://packagist.org) and you'd install it via composer. By default that will put it in a vendor folder in your plugin.