diff --git a/lib/letsencrypt.php b/lib/letsencrypt.php
new file mode 100644
index 0000000..2bf96ac
--- /dev/null
+++ b/lib/letsencrypt.php
@@ -0,0 +1,56 @@
+<?php
+namespace lib;
+
+/**
+ * LetsEncrypt
+ */
+class LetsEncrypt
+{
+    const HTTP_OK = 200;
+    const HTTP_CHALLENGE_URL = '/.well-known/acme-challenge/';
+    /**
+     * perform a cURL call on the remote resource
+     * the cURL call follows redirections and pushes the last valid URL to an array
+     * @param  Array  $domains list of domains
+     * @return Array  $checked_domains list of checked domains
+     */
+    public function checkRemoteResourceAvailability($domains)
+    {
+        $curl_multi = curl_multi_init();
+        $curl_handles = array();
+        $checked_domains = array();
+
+        foreach ($domains as $key => $domain) {
+            $curl_handles[$key] = curl_init($domain . self::HTTP_CHALLENGE_URL);
+
+            // setting cURL options
+            curl_setopt($curl_handles[$key], CURLOPT_TIMEOUT, 3);
+            curl_setopt($curl_handles[$key], CURLOPT_HEADER, true);
+            curl_setopt($curl_handles[$key], CURLOPT_NOBODY, true);
+            curl_setopt($curl_handles[$key], CURLOPT_SSL_VERIFYPEER, false);
+            curl_setopt($curl_handles[$key], CURLOPT_FOLLOWLOCATION, true);
+            curl_setopt($curl_handles[$key], CURLOPT_MAXREDIRS, 3);
+            curl_setopt($curl_handles[$key], CURLOPT_REDIR_PROTOCOLS, CURLPROTO_HTTP, CURLPROTO_HTTPS);
+            curl_setopt($curl_handles[$key], CURLOPT_RETURNTRANSFER, true);
+
+            curl_multi_add_handle($curl_multi, $curl_handles[$key]);
+        }
+
+        do {
+            curl_multi_exec($curl_multi, $active);
+        } while ($active);
+
+        foreach ($curl_handles as $curl_handle) {
+            $returned_http_code = curl_getinfo($curl_handle, CURLINFO_HTTP_CODE);
+            $returned_http_url = curl_getinfo($curl_handle, CURLINFO_EFFECTIVE_URL);
+
+            if ($returned_http_code === self::HTTP_OK && strpos($returned_http_url, self::HTTP_CHALLENGE_URL)) {
+                array_push($checked_domains, $returned_http_url);
+            }
+            curl_multi_remove_handle($curl_multi, $curl_handle);
+        }
+        curl_multi_close($curl_multi);
+
+        return $checked_domains;
+    }
+}