diff --git a/README.md b/README.md
index 41056cd..531508a 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,14 @@
 # [auth.rxbn.de](https://auth.rxbn.de) - Single sign-on (SSO) Service
 
-Single sign-on authentication and authorization service for rxbn.de services
+Single sign-on authentication service for rxbn.de services
+
+# Environment variables
+- __*DB_URL*__ := [MongoDB Connection URI String Format](https://docs.mongodb.com/manual/reference/connection-string/), ex.: mongodb://mongoDBUser:mongoDBPassword@localhost:27017/admin
+- __*DB_NAME*__ := MongoDB Database, ex.: authRxbn
+- __*SESSION_KEY*__ := SessionKey to encrypt sessions
+- __*COOKIE_KEY*__ := CookieKey to encrypt cookies
+- __*PROMETHEUS_USER*__ := PrometheusUser for basic authentication on prometheus endpoints, ex.: test
+- __*PROMETHEUS_PW*__ := PrometheusPassword for basic authentication on prometheus endpoints, ex.: test
 
 # start server
 ## regular