diff --git a/README.md b/README.md
index 0665736..fc60d93 100644
--- a/README.md
+++ b/README.md
@@ -5,3 +5,37 @@ A (hopefully soon) fully featured  selft-hosted web interface and server-backend
 # State of development
 
 - interface and backend planned
+
+# API docs
+
+## location data
+- id
+- locationname
+- latitude
+- longitude
+- countryname
+- measvalues
+    - measvalue
+    - sensorid
+    - timestamp
+- sensors
+    - id
+    - added
+    - userid
+    - sensorname
+    - property ('indoor' || 'sunny' || 'shadow' )
+    - valuetypeid
+- valuetypes
+    - id
+    - valuetype ('temperature' || 'humidity')
+    - valunit (html coding)
+    - displayproperty
+        - widget (properties for small widget)
+            - type ('doughnut' || 'number')
+            - properties (chartjs dataset properties if type is a chartjs type)
+        - chart (properties for large chart)
+            - type ('scatter')
+            - properties (chartjs dataset properties)
+- range (actual range of present measvalues)
+    - from
+    - to