diff --git a/src/API.hpp b/src/API.hpp
index a53ca3c..20e9e41 100644
--- a/src/API.hpp
+++ b/src/API.hpp
@@ -12,10 +12,34 @@
 
 namespace fw
 {
+    /**
+     * @brief The API to create, edit or remove firewall rules
+     * @author Florian Hoss
+     *
+     */
     class API
     {
     public:
+        /**
+         * @brief Construct a new API object
+         * assign ip and port to generate endpoint list,
+         * setup authentication,
+         * create WebServer,
+         * setup routing
+         *
+         * @param cert
+         * @param key
+         * @param username
+         * @param password
+         * @param ip
+         * @param port
+         */
         API(Firewall *, const char *cert, const char *key, const char *username, const char *password, const String ip, const uint16_t port = 8080);
+
+        /**
+         * @brief Destroy the API object
+         *
+         */
         ~API();
 #ifdef ESP8266
         void handle_client();
@@ -36,30 +60,164 @@ namespace fw
         String json_response_type = "application/json; charset=utf-8";
         const char *TAG = "[API]";
 
+        /**
+         * @brief Get the url base string
+         * e.g. http://0.0.0.0:8080/api
+         *
+         * @return String
+         */
         String get_url_base();
+
+        /**
+         * @brief Set up authentication
+         *
+         * @param username
+         * @param password
+         * @return ok_t
+         */
         ok_t setup_auth(const char *username, const char *password);
+
+        /**
+         * @brief check if request to API can proceed or needs to stop
+         *
+         * @return auth_t
+         */
         auth_t check_auth();
 
+        /**
+         * @brief Set up the routing/endpoints and encryption
+         *
+         * @param cert
+         * @param key
+         */
         void setup_routing(const char *cert, const char *key);
+
+        /**
+         * @brief add endpoint information to linked list
+         * that is used for the /api endpoint
+         *
+         * @param uri
+         * @param method
+         * @param description
+         */
         void add_endpoint_to_list(const String uri, const char *method, const char *description);
+
+        /**
+         * @brief handling not found
+         */
         void not_found_handler();
+
+        /**
+         * @brief GET handler to retrieve endpoint list
+         */
         void get_endpoint_list_handler();
+
+        /**
+         * @brief GET handler to retrieve single firewall rule
+         */
         void get_firewall_rule_handler();
+
+        /**
+         * @brief GET handler to retrieve firewall rules
+         */
         void get_firewall_rules_handler();
+
+        /**
+         * @brief POST handler to create firewall rule
+         */
         void post_firewall_handler();
+
+        /**
+         * @brief PUT handler to update firewall rule
+         */
         void put_firewall_handler();
+        /**
+         * @brief handling not found
+         */
         void delete_firewall_handler();
 
+        /**
+         * @brief check if request to create/update firewall rule
+         * has all required parameter
+         *
+         * @return true
+         * @return false
+         */
         bool request_has_all_firewall_parameter();
+
+        /**
+         * @brief add another attribute to the json object
+         *
+         * @param key
+         * @param value
+         * @param last
+         * @return String
+         */
         String json_new_attribute(String key, String value, bool last = false);
+
+        /**
+         * @brief add another attribute to the json object
+         *
+         * @param key
+         * @param value
+         * @param last
+         * @return String
+         */
         String json_new_attribute(String key, uint32_t value, bool last = false);
+
+        /**
+         * @brief json response to send any string and response code
+         *
+         * @param serialized_string
+         * @param response_code
+         */
         void json_generic_response(String serialized_string, const uint16_t response_code);
+
+        /**
+         * @brief json response that wraps the message in array brackets
+         *
+         * @param serialized_string
+         * @param response_code
+         */
         void json_array_response(String serialized_string, const uint16_t response_code);
+
+        /**
+         * @brief json response to send message as json object
+         *
+         * @param message
+         * @param response_code
+         */
         void json_message_response(String message, const uint16_t response_code);
 
+        /**
+         * @brief construct a firewall rule as json object
+         *
+         * @param rule_ptr
+         * @return String
+         */
         String construct_json_firewall_rule(firewall_rule_t *rule_ptr);
+
+        /**
+         * @brief construct array of all firewall rules as json object
+         *
+         * @return String
+         */
         String construct_json_firewall();
+
+        /**
+         * @brief construct an API endpoint as json object
+         *
+         * @param api_ptr
+         * @return String
+         */
         String construct_json_api_endpoint(api_endpoint_t *api_ptr);
+
+        /**
+         * @brief construct array of all endpoints as json object
+         *
+         * @param api_ptr
+         * @return String
+         */
         String construct_json_api();
     };
 }
diff --git a/src/Utils.hpp b/src/Utils.hpp
index ffe0970..2604b8b 100644
--- a/src/Utils.hpp
+++ b/src/Utils.hpp
@@ -78,12 +78,53 @@ namespace fw
         struct api_endpoints *next;
     } api_endpoint_t;
 
+    /**
+     * @brief converting protocol type to string
+     *
+     * @param protocol
+     * @return String
+     */
     String protocol_to_string(firewall_protocol_t &protocol);
+
+    /**
+     * @brief converting string to protocol type
+     *
+     * @param protocol
+     * @return firewall_protocol_t
+     */
     firewall_protocol_t string_to_protocol(String &protocol);
+
+    /**
+     * @brief converting target type to string
+     *
+     * @param target
+     * @return String
+     */
     String target_to_string(firewall_target_t &target);
+
+    /**
+     * @brief converting string to target type
+     *
+     * @param target
+     * @return firewall_target_t
+     */
     firewall_target_t string_to_target(String &target);
-    String response_code_to_string(const uint16_t response_code);
+
+    /**
+     * @brief running an endless loop to prevent further damage
+     *
+     */
     void endless_loop();
+
+    /**
+     * @brief returns if number is between or equal to lower and upper
+     *
+     * @param number
+     * @param lower
+     * @param upper
+     * @return true
+     * @return false
+     */
     bool is_in_range(const uint16_t number, const uint16_t lower, const uint16_t upper);
 }