diff --git a/src/MD_STD.php b/src/MD_STD.php
index 1e6b91e..b16e1ea 100644
--- a/src/MD_STD.php
+++ b/src/MD_STD.php
@@ -174,6 +174,39 @@ final class MD_STD {
 
     }
 
+    /**
+     * Function checking if a string contains another in a case-insensitive way.
+     *
+     * @param string $haystack String to check.
+     * @param string $needle   Potential start of $haystack.
+     *
+     * @return boolean
+     */
+    public static function stri_contains(string $haystack, string $needle):bool {
+
+        if (stripos($haystack, $needle) === false) return false;
+        return true;
+
+    }
+
+    /**
+     * Function checking if a string contains any of a given set of strings in a
+     * case-insensitive way.
+     *
+     * @param string   $haystack String to check.
+     * @param string[] $needles  Potential values contained in haystack.
+     *
+     * @return boolean
+     */
+    public static function stri_contains_any(string $haystack, array $needles):bool {
+
+        foreach ($needles as $needle) {
+            if (self::stri_contains($haystack, $needle) === true) return true;
+        }
+        return false;
+
+    }
+
     /**
      * Type-safe(r) wrapper around preg_replace.
      *