diff --git a/index.md b/index.md
index e8f3ec16bf..b9bf3ef045 100644
--- a/index.md
+++ b/index.md
@@ -19,6 +19,7 @@ A JSON-based encoding for 3D city models
 [Getting started]({{ '/tutorials/getting-started/' | prepend: site.baseurl }}){: .btn .fs-5 .mb-4 .mb-md-0 .mr-2 } 
 [Web-viewer](https://ninja.cityjson.org/){: .btn  .fs-5 .mb-4 .mb-md-0 .mr-2}
 [Validator](https://validator.cityjson.org/){: .btn  .fs-5 .mb-4 .mb-md-0 .mr-2}
+[cjio](https://github.com/cityjson/cjio){: .btn  .fs-5 .mb-4 .mb-md-0 .mr-2}
 
 
 ---