WC_Admin_Settings

The main class in charge of the settings in WooCommerce is WC_Admin_Settings.

Path to the file:

plugins/woocommerce/includes/admin/class-wc-admin-settings.php

Useful methods:

WC_Admin_Settings::add_message();
WC_Admin_Settings::add_error();

WC_Settings_Page

And there’s a class responsible for the tabs on the Settings page: WC_Settings_Page.

Path to the file:

/plugins/woocommerce/includes/admin/settings/class-wc-settings-page.php

There are 9 default tabs:

Shipping and Gateways

There was created a special abstract class WC_Settings_API for shipping and gateways.

Path to the file:

/plugins/woocommerce/includes/abstracts/abstract-wc-settings-api.php

There, we can find process_admin_options() method used to save options.

We can also see two classes extended from WC_Settings_API:

WC_Payment_Gateway
WC_Shipping_Method