diff --git a/README.md b/README.md
index 4b8d5d3..50e19c8 100644
--- a/README.md
+++ b/README.md
@@ -20,3 +20,48 @@ All honour for this working MQTT client library goes to Nick O'Leary,
 all blame for bugs in the C port shall go to me.
 
 
+## API
+
+
+The library provides the following functions:
+
+
+    void mqttClientInit(mqttClient_t *mqttClient, client_t *client, callback_t callback);
+
+Initializes the MQTT client, handover a client handle according to the definition
+from ``platformAdaption.h`` and a callback function for incoming messages.
+
+Implement this callback function for incoming messages with this footprint:
+
+    typedef void (*callback_t)(char*, uint8_t*, uint16_t);
+
+
+
+
+    bool mqttConnect(mqttClient_t *mqttClient, 
+             uint8_t *address, uint16_t port,
+             const char *id,
+             const char *user, const char *pass,
+             const char *willTopic, uint8_t willQos,
+             bool willRetain, const char *willMessage,
+             bool cleanSession);
+
+
+    void mqttDisconnect(mqttClient_t *mqttClient);
+
+    bool publish(mqttClient_t *mqttClient,
+             const char *topic, 
+             const uint8_t *payload, uint16_t plength,
+             bool retained);
+
+    bool subscribe(mqttClient_t *mqttClient,
+               const char *topic, uint8_t qos);
+    
+    bool unsubscribe(mqttClient_t *mqttClient,
+                 const char* topic);
+
+    bool mqttLoop(mqttClient_t *mqttClient);
+
+    bool mqttConnected(mqttClient_t *mqttClient);
+
+    
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