diff --git a/README.md b/README.md
index 05c605a..4dcf83c 100644
--- a/README.md
+++ b/README.md
@@ -2,3 +2,9 @@
 
 Validate Netz39 entities JSON.
 
+## Running the Service
+
+### Configuration
+
+The service is configured via the following environment variables:
+* `PORT`: Service port. defaults to 8080