diff --git a/fast.php b/fast.php
index fc654151..d412cdbe 100644
--- a/fast.php
+++ b/fast.php
@@ -31,6 +31,8 @@
 	require_once FASTWC_PATH . 'includes/assets.php';
 	// Loads fast utilities.
 	require_once FASTWC_PATH . 'includes/utilities.php';
+	// Add suppot for multicurrency.
+	require_once FASTWC_PATH . 'includes/multicurrency.php';
 	// Adds Fast Checkout button to store.
 	require_once FASTWC_PATH . 'includes/checkout.php';
 	// Adds Fast Login button to store.
diff --git a/includes/checkout.php b/includes/checkout.php
index c83bf1e2..21ec3c6f 100644
--- a/includes/checkout.php
+++ b/includes/checkout.php
@@ -150,10 +150,14 @@ function fastwc_woocommerce_before_checkout_form() {
  *
  * @param WC_Data         $order   Object object.
  * @param WP_REST_Request $request Request object.
+ *
+ * @return WC_Data
  */
 function fastwc_woocommerce_rest_pre_insert_shop_order_object( $order, $request ) {
 
-	fastwc_log_debug( 'Request object: ' . print_r( $request, true ) ); // phpcs:ignore
+	$order = fastwc_maybe_update_order_for_multicurrency( $order, $request );
+
+	fastwc_log_debug( 'Request object: ' . print_r( $request, true ) );
 
 	fastwc_log_debug( 'fastwc_woocommerce_rest_pre_insert_shop_order_object ' . print_r( $order, true ) ); // phpcs:ignore
 
diff --git a/includes/multicurrency.php b/includes/multicurrency.php
new file mode 100644
index 00000000..98beb3fd
--- /dev/null
+++ b/includes/multicurrency.php
@@ -0,0 +1,173 @@
+<?php
+/**
+ * Add support for multicurrency functionality.
+ *
+ * @package fast
+ */
+
+// Add base multicurrency class.
+require_once FASTWC_PATH . 'includes/multicurrency/class-base.php';
+// Add support for Currency Switcher for WooCommerce plugin.
+require_once FASTWC_PATH . 'includes/multicurrency/class-currency-switcher-woocommerce.php';
+// Add support for WooCommerce Currency Switcher plugin.
+require_once FASTWC_PATH . 'includes/multicurrency/class-woocommerce-currency-switcher.php';
+// Add support for Price Based on Country for WooCommerce plugin.
+require_once FASTWC_PATH . 'includes/multicurrency/class-woocommerce-product-price-based-on-countries.php';
+
+/**
+ * Checks if multicurrency support is disabled.
+ *
+ * @return bool True if multicurrency support is disabled. False otherwise.
+ */
+function fastwc_is_multicurrency_support_disabled() {
+	$fastwc_disable_multicurrency = get_option( FASTWC_SETTING_DISABLE_MULTICURRENCY, false );
+
+	if ( ! empty( $fastwc_disable_multicurrency ) ) {
+		return true;
+	}
+
+	return false;
+
+}
+
+/**
+ * Maybe update order for multicurrency.
+ *
+ * @param WC_Data         $order    The order to check.
+ * @param WP_REST_Request $request  Request object.
+ *
+ * @return WC_Data
+ */
+function fastwc_maybe_update_order_for_multicurrency( $order, $request ) {
+	$multicurrency_disabled = fastwc_is_multicurrency_support_disabled();
+
+	// Do nothing if multicurrency is disabled.
+	if ( false === $multicurrency_disabled ) {
+		$wc_currency    = get_woocommerce_currency();
+		$order_currency = fastwc_get_order_currency( $order );
+
+		if (
+			! empty( $order_currency ) // Make sure the order currency is set.
+			&& $wc_currency !== $order_currency // Make sure the order currency is not the default currency.
+		) {
+			$order = fastwc_update_order_for_multicurrency( $order, $request );
+		}
+	}
+
+	return $order;
+}
+
+/**
+ * Get the order currency.
+ *
+ * @param WC_Data $order The order to check.
+ *
+ * @return string
+ */
+function fastwc_get_order_currency( $order ) {
+	$wc_currency = get_woocommerce_currency();
+
+	return method_exists( $order, 'get_currency' ) ? $order->get_currency() : $wc_currency;
+}
+
+/**
+ * Update the order for multicurrency.
+ *
+ * @param WC_Data         $order                The order to check.
+ * @param WP_REST_Request $request              Request object.
+ *
+ * @return WC_Data
+ */
+function fastwc_update_order_for_multicurrency( $order, $request ) {
+
+	/**
+	 * Maybe update the order from the multicurrency plugin.
+	 *
+	 * @param WC_Data         $order                The order to check.
+	 * @param WP_REST_Request $request              Request object.
+	 */
+	$order = apply_filters(
+		'fastwc_update_order_for_multicurrency',
+		$order,
+		$request
+	);
+
+	foreach ( $order->get_items() as $item_id => $item ) {
+		$product  = method_exists( $item, 'get_product' ) ? $item->get_product() : null;
+		$quantity = method_exists( $item, 'get_quantity' ) ? (int) $item->get_quantity() : 0;
+
+		if ( ! empty( $product ) ) {
+			/**
+			 * Get the price from the multicurrency plugin.
+			 *
+			 * @param string     $price   Value of the price.
+			 * @param WC_Product $product The product object.
+			 * @param WC_Data    $order   The order to check.
+			 * @param WC_Request $request Request object.
+			 */
+			$price = apply_filters(
+				'fastwc_update_price_for_multicurrency',
+				$product->get_price(),
+				$product,
+				$order,
+				$request
+			);
+
+			// Calculate the price by multiplying by quantity.
+			$new_price = $price * $quantity;
+
+			// Set the new price.
+			$item->set_subtotal( $new_price );
+			$item->set_total( $new_price );
+
+			// Make new tax calculations.
+			$item->calculate_taxes();
+
+			// Save the item data.
+			$item->save();
+		}
+	}
+
+	$order->calculate_totals();
+
+	return $order;
+}
+
+/**
+ * Maybe update shipping rates for multicurrency.
+ *
+ * @param array           $rate_info   The rate response information.
+ * @param string          $wc_currency The default WooCommerce currency.
+ * @param string          $currency    The customer currency.
+ * @param WP_REST_Request $request     The request object.
+ *
+ * @return array
+ */
+function fastwc_maybe_update_shipping_rate_for_multicurrency( $rate_info, $wc_currency, $currency, $request ) {
+	$multicurrency_disabled = fastwc_is_multicurrency_support_disabled();
+
+	// Do nothing if multicurrency is disabled.
+	if (
+		false === $multicurrency_disabled
+		&& ! empty( $currency ) // Make sure the customer currency is set.
+		&& $wc_currency !== $currency // Make sure the customer currency is not the default currency.
+	) {
+		/**
+		 * Update shipping rates for multicurrency.
+		 *
+		 * @param array           $rate_info The rate response information.
+		 * @param string          $currency  The customer currency.
+		 * @param WP_REST_Request $request   The request object.
+		 *
+		 * @return array
+		 */
+		$rate_info = apply_filters(
+			'fastwc_update_shipping_rate_for_multicurrency',
+			$rate_info,
+			$currency,
+			$request
+		);
+	}
+
+	return $rate_info;
+}
diff --git a/includes/multicurrency/class-base.php b/includes/multicurrency/class-base.php
new file mode 100644
index 00000000..a82f05b6
--- /dev/null
+++ b/includes/multicurrency/class-base.php
@@ -0,0 +1,121 @@
+<?php
+/**
+ * Multicurrency support plugin base class.
+ *
+ * @package Fast
+ */
+
+namespace FastWC\Multicurrency;
+
+/**
+ * Base class for supporting third party multicurrency plugins.
+ */
+class Base {
+
+	/**
+	 * Create the class.
+	 */
+	public function __construct() {
+		add_filter( 'fastwc_update_price_for_multicurrency', array( $this, 'update_price' ), 10, 4 );
+		add_filter( 'fastwc_update_shipping_rate_for_multicurrency', array( $this, 'update_shipping' ), 10, 3 );
+		add_filter( 'fastwc_update_order_for_multicurrency', array( $this, 'update_order' ), 10, 2 );
+	}
+
+	/**
+	 * Check if the third-party plugin is active.
+	 *
+	 * @return bool
+	 */
+	protected function is_active() {
+		return false;
+	}
+
+	/**
+	 * Filter handler for updating the product price for multicurrency.
+	 *
+	 * @param string     $price   Value of the price.
+	 * @param WC_Product $product The product object.
+	 * @param WC_Data    $order   The order to check.
+	 * @param WC_Request $request Request object.
+	 *
+	 * @return string
+	 */
+	public function update_price( $price, $product, $order, $request ) {
+
+		if ( $this->is_active() ) {
+			return $this->do_update_price( $price, $product, $order, $request );
+		}
+
+		return $price;
+	}
+
+	/**
+	 * Update the product price for multicurrency.
+	 *
+	 * @param string     $price   Value of the price.
+	 * @param WC_Product $product The product object.
+	 * @param WC_Data    $order   The order to check.
+	 * @param WC_Request $request Request object.
+	 *
+	 * @return string
+	 */
+	protected function do_update_price( $price, $product, $order, $request ) {
+		return $price;
+	}
+
+	/**
+	 * Filter handler for updating the shipping rate for multicurrency.
+	 *
+	 * @param array           $rate_info The rate response information.
+	 * @param string          $currency  The customer currency.
+	 * @param WP_REST_Request $request   The request object.
+	 *
+	 * @return array
+	 */
+	public function update_shipping( $rate_info, $currency, $request ) {
+
+		if ( $this->is_active() ) {
+			return $this->do_update_shipping( $rate_info, $currency, $request );
+		}
+
+		return $rate_info;
+	}
+
+	/**
+	 * Update the shipping rate for multicurrency.
+	 *
+	 * @param array           $rate_info The rate response information.
+	 * @param string          $currency  The customer currency.
+	 * @param WP_REST_Request $request   The request object.
+	 *
+	 * @return array
+	 */
+	protected function do_update_shipping( $rate_info, $currency, $request ) {
+		return $rate_info;
+	}
+
+	/**
+	 * Filter handler for updating the order for multicurrency.
+	 *
+	 * @param WC_Data         $order                The order to check.
+	 * @param WP_REST_Request $request              Request object.
+	 */
+	public function update_order( $order, $request ) {
+
+		if ( $this->is_active() ) {
+			return $this->do_update_order( $order, $request );
+		}
+
+		return $order;
+	}
+
+	/**
+	 * Update the order for multicurrency.
+	 *
+	 * @param WC_Data         $order                The order to check.
+	 * @param WP_REST_Request $request              Request object.
+	 */
+	protected function do_update_order( $order, $request ) {
+		return $order;
+	}
+}
diff --git a/includes/multicurrency/class-currency-switcher-woocommerce.php b/includes/multicurrency/class-currency-switcher-woocommerce.php
new file mode 100644
index 00000000..2b13abf9
--- /dev/null
+++ b/includes/multicurrency/class-currency-switcher-woocommerce.php
@@ -0,0 +1,70 @@
+<?php
+/**
+ * Add support for Currency Switcher for WooCommerce plugin.
+ *
+ * @see https://wordpress.org/plugins/currency-switcher-woocommerce/
+ *
+ * @package Fast
+ */
+
+namespace FastWC\Multicurrency;
+
+/**
+ * Class to support Currency Switcher for WooCommerce.
+ */
+class Currency_Switcher_Woocommerce extends Base {
+
+	/**
+	 * Check if the third-party plugin is active.
+	 *
+	 * @return bool
+	 */
+	protected function is_active() {
+		return class_exists( 'Alg_WC_Currency_Switcher' );
+	}
+
+	/**
+	 * Update the product price for multicurrency.
+	 *
+	 * @param string     $price   Value of the price.
+	 * @param WC_Product $product The product object.
+	 * @param WC_Data    $order   The order to check.
+	 * @param WC_Request $request Request object.
+	 *
+	 * @return string
+	 */
+	protected function do_update_price( $price, $product, $order, $request ) {
+
+		$order_currency = \fastwc_get_order_currency( $order );
+		$new_price      = \alg_get_product_price_by_currency( $price, $order_currency, $product, true );
+
+		if ( ! empty( $new_price ) ) {
+			return $new_price;
+		}
+
+		return $price;
+	}
+
+	/**
+	 * Update the shipping rate for multicurrency.
+	 *
+	 * @param array           $rate_info The rate response information.
+	 * @param string          $currency  The customer currency.
+	 * @param WP_REST_Request $request   The request object.
+	 *
+	 * @return array
+	 */
+	protected function do_update_shipping( $rate_info, $currency, $request ) {
+
+		$rate_info['price'] = \alg_get_product_price_by_currency_global( $rate_info['price'], $currency );
+		if ( ! empty( $rate_info['taxes'] ) ) {
+			$rate_taxes = $rate_info['taxes'];
+
+			foreach ( $rate_taxes as $rate_tax_id => $rate_tax ) {
+				$rate_info['taxes'][ $rate_tax_id ] = \alg_get_product_price_by_currency_global( $rate_tax, $currency );
+			}
+		}
+
+		return $rate_info;
+	}
+}
diff --git a/includes/multicurrency/class-woocommerce-currency-switcher.php b/includes/multicurrency/class-woocommerce-currency-switcher.php
new file mode 100644
index 00000000..690123f1
--- /dev/null
+++ b/includes/multicurrency/class-woocommerce-currency-switcher.php
@@ -0,0 +1,71 @@
+<?php
+/**
+ * Add support for WooCommerce Currency Switcher plugin.
+ *
+ * @see https://wordpress.org/plugins/woocommerce-currency-switcher/
+ *
+ * @package fast
+ */
+
+namespace FastWC\Multicurrency;
+
+/**
+ * Class to support WooCommerce Currency Switcher.
+ */
+class Woocommerce_Currency_Switcher extends Base {
+
+	/**
+	 * Check if the third-party plugin is active.
+	 *
+	 * @return bool
+	 */
+	protected function is_active() {
+		return class_exists( 'WOOCS_STARTER' );
+	}
+
+	/**
+	 * Update the product price for multicurrency.
+	 *
+	 * @param string     $price   Value of the price.
+	 * @param WC_Product $product The product object.
+	 * @param WC_Data    $order   The order to check.
+	 * @param WC_Request $request Request object.
+	 *
+	 * @return string
+	 */
+	protected function do_update_price( $price, $product, $order, $request ) {
+		global $WOOCS; // phpcs:ignore WordPress.NamingConventions.ValidVariableName.VariableNotSnakeCase
+
+		$order_currency = \fastwc_get_order_currency( $order );
+
+		$_REQUEST['woocs_raw_woocommerce_price_currency'] = $order_currency;
+
+		return $WOOCS->raw_woocommerce_price( $price, $product ); // phpcs:ignore WordPress.NamingConventions.ValidVariableName.VariableNotSnakeCase
+	}
+
+	/**
+	 * Update the shipping rate for multicurrency.
+	 *
+	 * @param array           $rate_info The rate response information.
+	 * @param string          $currency  The customer currency.
+	 * @param WP_REST_Request $request   The request object.
+	 *
+	 * @return array
+	 */
+	protected function do_update_shipping( $rate_info, $currency, $request ) {
+		global $WOOCS; // phpcs:ignore WordPress.NamingConventions.ValidVariableName.VariableNotSnakeCase
+
+		$_REQUEST['woocs_raw_woocommerce_price_currency'] = $currency;
+
+		$rate_info['price'] = $WOOCS->raw_woocommerce_price( $rate_info['price'] ); // phpcs:ignore WordPress.NamingConventions.ValidVariableName.VariableNotSnakeCase
+		if ( ! empty( $rate_info['taxes'] ) ) {
+			$rate_taxes = $rate_info['taxes'];
+
+			foreach ( $rate_taxes as $rate_tax_id => $rate_tax ) {
+				$rate_info['taxes'][ $rate_tax_id ] = $WOOCS->raw_woocommerce_price( $rate_tax ); // phpcs:ignore WordPress.NamingConventions.ValidVariableName.VariableNotSnakeCase
+			}
+		}
+
+		return $rate_info;
+	}
+}
diff --git a/includes/multicurrency/class-woocommerce-product-price-based-on-countries.php b/includes/multicurrency/class-woocommerce-product-price-based-on-countries.php
new file mode 100644
index 00000000..4575e43f
--- /dev/null
+++ b/includes/multicurrency/class-woocommerce-product-price-based-on-countries.php
@@ -0,0 +1,188 @@
+<?php
+/**
+ * Add support for Price Based on Country for WooCommerce plugin.
+ *
+ * @see https://wordpress.org/plugins/woocommerce-product-price-based-on-countries/
+ *
+ * @package fast
+ */
+
+namespace FastWC\Multicurrency;
+
+/**
+ * Class to support WooCommerce Currency Switcher.
+ */
+class Woocommerce_Product_Price_Based_On_Countries extends Base {
+
+	/**
+	 * Check if the third-party plugin is active.
+	 *
+	 * @return bool
+	 */
+	protected function is_active() {
+		return class_exists( 'WC_Product_Price_Based_Country' );
+	}
+
+	/**
+	 * Update the product price for multicurrency.
+	 *
+	 * @param string     $price   Value of the price.
+	 * @param WC_Product $product The product object.
+	 * @param WC_Data    $order   The order to check.
+	 * @param WC_Request $request Request object.
+	 *
+	 * @return string
+	 */
+	protected function do_update_price( $price, $product, $order, $request ) {
+		\fastwc_log_debug( 'Price Based on Country multicurrency plugin - Update price' );
+		\fastwc_log_debug( 'Price Before Conversion: ' . $price );
+
+		$zone = $this->get_zone( $request );
+		\fastwc_log_debug( 'Zone: ' . print_r( $zone, true ) ); // phpcs:ignore
+
+		if ( ! empty( $zone ) ) {
+			\fastwc_log_debug( 'Setting price for zone' );
+			$price = $zone->get_post_price( $product->get_id(), '_price' );
+		}
+
+		\fastwc_log_debug( 'Price After Conversion: ' . $price );
+
+		return $price;
+	}
+
+	/**
+	 * Update the shipping rate for multicurrency.
+	 *
+	 * @param array           $rate_info The rate response information.
+	 * @param string          $currency  The customer currency.
+	 * @param WP_REST_Request $request   The request object.
+	 *
+	 * @return array
+	 */
+	protected function do_update_shipping( $rate_info, $currency, $request ) {
+		$country = $this->get_country( $request );
+
+		\fastwc_log_debug( 'Price Based on Country multicurrency plugin - Update shipping' );
+		\fastwc_log_debug( 'Shipping Before Conversion: ' . print_r( $rate_info, true ) ); // phpcs:ignore
+
+		$zone = $this->get_zone( $request );
+		\fastwc_log_debug( 'Zone: ' . print_r( $zone, true ) ); // phpcs:ignore
+
+		if ( ! empty( $zone ) ) {
+			$rate_info['price'] = $zone->get_exchange_rate_price( $rate_info['price'] );
+
+			if ( ! empty( $rate_info['taxes'] ) ) {
+				$rate_taxes = $rate_info['taxes'];
+
+				foreach ( $rate_taxes as $rate_tax_id => $rate_tax ) {
+					$rate_info['taxes'][ $rate_tax_id ] = $zone->get_exchange_rate_price( $rate_tax );
+				}
+			}
+		}
+
+		\fastwc_log_debug( 'Shipping After Conversion: ' . print_r( $rate_info, true ) ); // phpcs:ignore
+
+		return $rate_info;
+	}
+
+	/**
+	 * Update the order for multicurrency.
+	 *
+	 * @param WC_Data         $order                The order to check.
+	 * @param WP_REST_Request $request              Request object.
+	 */
+	protected function do_update_order( $order, $request ) {
+		// Make sure the order currency is correct for the billing address zone.
+		$country = $this->get_country( $request );
+
+		if ( ! empty( $country ) ) {
+			$zone           = $this->get_zone( $request, false );
+			$order_currency = \fastwc_get_order_currency( $order );
+			$zone_currency  = $zone->get_currency();
+
+			// Change the order currency if it does not match the zone currenncy.
+			if ( ! empty( $zone ) && $order_currency !== $zone_currency ) {
+				$order->set_currency( $zone_currency );
+			}
+		}
+
+		return $order;
+	}
+
+	/**
+	 * Get the billing address country from the request.
+	 *
+	 * @param mixed $request The request object.
+	 *
+	 * @return string
+	 */
+	protected function get_country( $request ) {
+		$country = '';
+
+		$valid_based_on = array( 'billing', 'shipping' );
+		$based_on       = \get_option( 'wc_price_based_country_based_on', 'billing' );
+
+		// Make sure based on is billing or shipping.
+		if ( ! in_array( $based_on, $valid_based_on, true ) ) {
+			$based_on = 'billing';
+		}
+
+		if ( is_array( $request ) ) {
+			if ( ! empty( $request[ $based_on ]['country'] ) ) {
+				$country = $request[ $based_on ]['country'];
+			}
+		} elseif ( is_a( $request, 'WP_REST_Request' ) ) {
+			$params = $request->get_params();
+
+			if ( ! empty( $params[ $based_on ]['country'] ) ) {
+				$country = $params[ $based_on ]['country'];
+			}
+		}
+
+		return $country;
+	}
+
+	/**
+	 * Get the pricing zone from the request.
+	 *
+	 * @param mixed $request              The request object.
+	 * @param bool  $get_zone_by_currency Optional. Flag to get zone by currency.
+	 *
+	 * @return WCPBC_Pricing_Zone|WCPBC_Pricing_Zone_Pro
+	 */
+	protected function get_zone( $request, $get_zone_by_currency = true ) {
+		$country = $this->get_country( $request );
+
+		\fastwc_log_debug( 'Country: ' . $country );
+
+		$zone = false;
+
+		if ( ! empty( $country ) ) {
+			$zone = \wcpbc_get_zone_by_country( $country );
+			\fastwc_log_debug( 'Zone by country: ' . print_r( $zone, true ) ); // phpcs:ignore
+		}
+
+		// Maybe get the zone by currency.
+		if (
+			$get_zone_by_currency &&
+			(
+				empty( $zone ) ||
+				$order_currency !== $zone->get_currency()
+			)
+		) {
+			$zones = \WCPBC_Pricing_Zones::get_zones();
+
+			// Loop through the zones and get a zone by the currency.
+			foreach ( $zones as $_zone ) {
+				if ( $order_currency === $_zone->get_currency() ) {
+					$zone = $_zone;
+					\fastwc_log_debug( 'Zone by currency: ' . print_r( $zone, true ) ); // phpcs:ignore
+
+					break;
+				}
+			}
+		}
+
+		return $zone;
+	}
+}
diff --git a/includes/routes/class-base.php b/includes/routes/class-base.php
new file mode 100644
index 00000000..5fd21b86
--- /dev/null
+++ b/includes/routes/class-base.php
@@ -0,0 +1,95 @@
+<?php
+/**
+ * Base class for Fast route object.
+ *
+ * @package Fast
+ */
+
+namespace FastWC\Routes;
+
+/**
+ * Fast route base class.
+ */
+abstract class Base {
+
+	/**
+	 * Route namespace.
+	 *
+	 * @var string
+	 */
+	protected $namespace = FASTWC_ROUTES_BASE;
+
+	/**
+	 * Route name.
+	 *
+	 * @var string
+	 */
+	protected $route;
+
+	/**
+	 * Route methods.
+	 *
+	 * @var string
+	 */
+	protected $methods = 'GET';
+
+	/**
+	 * Route callback.
+	 *
+	 * @var callable
+	 */
+	protected $callback;
+
+	/**
+	 * Permission callback.
+	 *
+	 * @var callable
+	 */
+	protected $permission_callback = 'fastwc_api_permission_callback';
+
+	/**
+	 * Request object passed to the route endpoint.
+	 *
+	 * @var \WP_REST_Request
+	 */
+	protected $request;
+
+	/**
+	 * Route constructor, protected to prevent multiple instances.
+	 */
+	public function __construct() {
+		$this->init();
+		$this->register();
+	}
+
+	/**
+	 * Initialize the route arguments.
+	 */
+	protected function init() {
+		if ( empty( $this->callback ) ) {
+			$this->callback = array( $this, 'callback' );
+		}
+	}
+
+	/**
+	 * Register the route.
+	 */
+	protected function register() {
+		register_rest_route(
+			$this->namespace,
+			$this->route,
+			array(
+				'methods'             => $this->methods,
+				'callback'            => $this->callback,
+				'permission_callback' => $this->permission_callback,
+			)
+		);
+	}
+
+	/**
+	 * Route callback function.
+	 *
+	 * @param WP_REST_Request $request JSON request for shipping endpoint.
+	 */
+	abstract public function callback( $request );
+}
diff --git a/includes/routes/class-shipping.php b/includes/routes/class-shipping.php
index ce4b085f..49bd8332 100644
--- a/includes/routes/class-shipping.php
+++ b/includes/routes/class-shipping.php
@@ -10,7 +10,7 @@
 /**
  * Fast shipping route object.
  */
-class Shipping extends Route {
+class Shipping extends Base {
 
 	/**
 	 * Route name.
@@ -26,6 +26,20 @@ class Shipping extends Route {
 	 */
 	protected $methods = 'POST';
 
+	/**
+	 * Currency code.
+	 *
+	 * @var string
+	 */
+	protected $currency = '';
+
+	/**
+	 * WooCommerce base currency code.
+	 *
+	 * @var string
+	 */
+	protected $wc_currency = '';
+
 	/**
 	 * Given shipping address and product, attempts to calculate available shipping rates for the address.
 	 * Doesn't support shipping > 1 address.
@@ -42,6 +56,8 @@ public function callback( $request ) {
 		$params = $this->request->get_params();
 		$return = false;
 
+		$this->get_currency();
+
 		// This is needed for session to work.
 		\WC()->frontend_includes();
 
@@ -64,6 +80,34 @@ public function callback( $request ) {
 		return $return;
 	}
 
+	/**
+	 * Get the currency from the request object.
+	 */
+	protected function get_currency() {
+		if ( empty( $this->request ) ) {
+			return;
+		}
+
+		$params = $this->request->get_params();
+
+		// Maybe set the wc_currency parameter.
+		if ( empty( $this->wc_currency ) ) {
+			$this->wc_currency = \get_woocommerce_currency();
+		}
+
+		// Get the order ID from the request params.
+		$order_id = ! empty( $params['order_id'] ) ? $params['order_id'] : 0;
+
+		if ( empty( $order_id ) ) {
+			$this->currency = ! empty( $params['currency'] ) ? $params['currency'] : $this->wc_currency;
+		} else {
+			$order          = new \WC_Order( $order_id );
+			$this->currency = \fastwc_get_order_currency( $order );
+		}
+
+		\add_filter( 'woocommerce_currency', array( $this, 'update_woocommerce_currency' ), PHP_INT_MAX );
+	}
+
 	/**
 	 * Initialize the WC session.
 	 */
@@ -327,12 +371,38 @@ protected function get_rate_response( $rate ) {
 			'meta_data'     => $this->get_rate_meta_data( $rate ),
 		);
 
+		$rate_info = \fastwc_maybe_update_shipping_rate_for_multicurrency( $rate_info, $this->wc_currency, $this->currency, $this->request );
+
+		$rate_info['price'] = \wc_format_decimal( $rate_info['price'], 2 );
+		if ( ! empty( $rate_info['taxes'] ) ) {
+			$rate_taxes = $rate_info['taxes'];
+
+			foreach ( $rate_taxes as $rate_tax_id => $rate_tax ) {
+				$rate_info['taxes'][ $rate_tax_id ] = \wc_format_decimal( $rate_tax, 2 );
+			}
+		}
+
 		return array_merge(
 			$rate_info,
 			$this->get_store_currency_response()
 		);
 	}
 
+	/**
+	 * Update WC currency.
+	 *
+	 * @param string $currency The base currency.
+	 *
+	 * @return string
+	 */
+	public function update_woocommerce_currency( $currency ) {
+		if ( ! empty( $this->currency ) ) {
+			$currnecy = $this->currency;
+		}
+
+		return $currency;
+	}
+
 	/**
 	 * Prepares a list of store currency data to return in responses.
 	 *
@@ -340,6 +410,7 @@ protected function get_rate_response( $rate ) {
 	 */
 	protected function get_store_currency_response() {
 		$position = \get_option( 'woocommerce_currency_pos' );
+		$currency = ! empty( $this->currency ) ? $this->currency : \get_woocommerce_currency();
 		$symbol   = html_entity_decode( \get_woocommerce_currency_symbol( $currency ) );
 		$prefix   = '';
 		$suffix   = '';
@@ -362,7 +433,7 @@ protected function get_store_currency_response() {
 		}
 
 		return array(
-			'currency_code'               => \get_woocommerce_currency(),
+			'currency_code'               => $currency,
 			'currency_symbol'             => $symbol,
 			'currency_minor_unit'         => \wc_get_price_decimals(),
 			'currency_decimal_separator'  => \wc_get_price_decimal_separator(),
diff --git a/templates/buttons/fast-checkout-button.php b/templates/buttons/fast-checkout-button.php
index 67243019..cd609ad4 100644
--- a/templates/buttons/fast-checkout-button.php
+++ b/templates/buttons/fast-checkout-button.php
@@ -5,15 +5,20 @@
  * @package Fast
  */
 
-$fastwc_app_id         = fastwc_get_app_id();
-$product_id            = ! empty( $args['product_id'] ) ? absint( $args['product_id'] ) : 0;
-$variant_id            = ! empty( $args['variant_id'] ) ? absint( $args['variant_id'] ) : 0;
-$quantity              = ! empty( $args['quantity'] ) ? absint( $args['quantity'] ) : 0;
-$product_options       = ! empty( $args['product_options'] ) ? fastwc_get_normalized_product_options( $args['product_options'] ) : '';
-$fastwc_use_dark_mode  = fastwc_use_dark_mode( $product_id );
+$fastwc_app_id          = fastwc_get_app_id();
+$currency               = get_woocommerce_currency();
+$multicurrency_disabled = fastwc_is_multicurrency_support_disabled();
+$product_id             = ! empty( $args['product_id'] ) ? absint( $args['product_id'] ) : 0;
+$variant_id             = ! empty( $args['variant_id'] ) ? absint( $args['variant_id'] ) : 0;
+$quantity               = ! empty( $args['quantity'] ) ? absint( $args['quantity'] ) : 0;
+$product_options        = ! empty( $args['product_options'] ) ? fastwc_get_normalized_product_options( $args['product_options'] ) : '';
+$fastwc_use_dark_mode   = fastwc_use_dark_mode( $product_id );
 ?>
 	<fast-checkout-button
 		app_id="<?php echo esc_attr( $fastwc_app_id ); ?>"
+		<?php if ( false === $multicurrency_disabled ) : ?>
+		currency="<?php echo esc_attr( $currency ); ?>"
+		<?php endif; ?>
 		<?php if ( ! empty( $product_id ) ) : ?>
 		product_id="<?php echo esc_attr( $product_id ); ?>"
 			<?php if ( ! empty( $variant_id ) ) : ?>
diff --git a/templates/buttons/fast-checkout-cart-button.php b/templates/buttons/fast-checkout-cart-button.php
index f28f65ee..c4b2367c 100644
--- a/templates/buttons/fast-checkout-cart-button.php
+++ b/templates/buttons/fast-checkout-cart-button.php
@@ -5,23 +5,24 @@
  * @package Fast
  */
 
-$fastwc_app_id         = fastwc_get_app_id();
-$fastwc_cart_data      = fastwc_get_cart_data();
-$cart_data             = wp_json_encode( array_values( $fastwc_cart_data ) );
-$applied_coupons       = ! empty( WC()->cart ) ? WC()->cart->get_applied_coupons() : array();
-$applied_coupons_count = count( $applied_coupons );
-$fastwc_use_dark_mode  = fastwc_use_dark_mode();
+$fastwc_app_id          = fastwc_get_app_id();
+$fastwc_cart_data       = fastwc_get_cart_data();
+$cart_data              = wp_json_encode( array_values( $fastwc_cart_data ) );
+$applied_coupons        = ! empty( WC()->cart ) ? WC()->cart->get_applied_coupons() : array();
+$applied_coupons_count  = count( $applied_coupons );
+$currency               = get_woocommerce_currency();
+$multicurrency_disabled = fastwc_is_multicurrency_support_disabled();
+$fastwc_use_dark_mode   = fastwc_use_dark_mode();
 ?>
 	<fast-checkout-cart-button
 		app_id="<?php echo esc_attr( $fastwc_app_id ); ?>"
 		cart_data="<?php echo esc_attr( $cart_data ); ?>"
-		<?php
-		if ( 1 === $applied_coupons_count ) {
-			?>
-				coupon_code="<?php echo esc_attr( $applied_coupons[0] ); ?>"
-				<?php
-		}
-		?>
+		<?php if ( false === $multicurrency_disabled ) : ?>
+		currency="<?php echo esc_attr( $currency ); ?>"
+		<?php endif; ?>
+		<?php if ( 1 === $applied_coupons_count ) : ?>
+		coupon_code="<?php echo esc_attr( $applied_coupons[0] ); ?>"
+		<?php endif; ?>
 		<?php if ( $fastwc_use_dark_mode ) : ?>
 		dark
 		<?php endif; ?>