diff --git a/README.md b/README.md
index a1bb8a1..65808cd 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,10 @@ $ composer require elementsproject/lightning-strike-client-php
 
 ```php
 <?php
-$strike = new LightingStrikeClient('http://localhost:8009');
+// Initialize client
+$strike = new LightingStrikeClient('http://localhost:8009', '[TOKEN]');
+// alternatively, the token can be provided as part of URL:
+$strike = new LightingStrikeClient('http://api-token:[TOKEN]@localhost:8009');
 
 // Create invoice
 $invoice = $strike->invoice([ 'msatoshi' => 50, 'metadata' => [ 'customer' => 'Satoshi', 'products' => [ 'potato', 'chips' ] ] ]);
@@ -31,7 +34,7 @@ TODO: document missing methods
 ## Test
 
 ```bash
-$ STRIKE_URL=http://localhost:8009 phpunit test
+$ STRIKE_URL=http://api-token:[TOKEN]@localhost:8009 phpunit test
 ```
 
 ## License
diff --git a/client.php b/client.php
index 3008645..0bd74d1 100644
--- a/client.php
+++ b/client.php
@@ -4,8 +4,13 @@
 class LightningStrikeClient {
   protected $api;
 
-  public function __construct($url) {
-    $this->api = new RestClient([ 'base_url' => rtrim($url, '/') ]);
+  public function __construct($url, $api_token=null) {
+    $this->api = new RestClient([
+      'base_url' => rtrim($url, '/'),
+      'curl_options' => $api_token ? [
+        CURLOPT_USERPWD => 'api-token:' . $api_token
+      ] : []
+    ]);
   }
 
   /**