diff --git a/docs/composer/plugin/d4d/index.md b/docs/composer/plugin/d4d/index.md
index 0ea12331ef96015c9f16fe088ac49bee442e07ef..f5de36130c474b285e3e333cb1d3c3075bae157f 100644
--- a/docs/composer/plugin/d4d/index.md
+++ b/docs/composer/plugin/d4d/index.md
@@ -315,6 +315,36 @@ This will add another environment variable to the php container, define a second
 
 Please remember to update docker compose with `ahoy update` and then recreate your containers with `ahoy up` after changing these settings.
 
+### Adding Invoice Ninja
+
+To enable [Invoice Ninja](https://invoiceninja.com/), you can add this to `lakedrops.yml`:
+
+```in
+docker4drupal:
+invoiceninja:
+enable: true
+api_key: 'base64:THE KEY FROM YOUR IN INSTANCE'
+admin_name: admin@example.com
+admin_pass: INITIAL ADMIN PASSWORD
+mail:
+host: smtp.example.com
+port: 465
+user: USERNAME
+pass: PASSWORD
+security: ssl
+fromname: 'YOUR NAME'
+```
+
+After executing `a d4d update`, you will find the following Docker container in your console:
+
+```in
+✔ Container tierpension-haas-in-db-1        Started
+✔ Container tierpension-haas-in-app-1       Started
+✔ Container tierpension-haas-in-web-1       Started
+```
+
+You now can access Invoice Ninja by URL: `http(s)://invoice-<your-domain>`.
+
 ### More configuration tweaks
 
 #### Customizing the apache config