diff --git a/README.md b/README.md
index 60d1ab0..d52de03 100644
--- a/README.md
+++ b/README.md
@@ -163,7 +163,7 @@ There are a few builtin decoders and post hooks, to support some common use
 cases. For example decoding events from a oci distribution registry, or opening
 a pull request on github.
 
-The starlark code for the builtins can be reviewed in the [builtin](./builtin)
+The starlark code for the builtins can be reviewed in the [builtin](./plugin/builtin)
 directory.
 
 #### Decoder
diff --git a/plugin/builtin/starlark/decoder.harbor@v1.star b/plugin/builtin/starlark/decoder.harbor@v1.star
new file mode 100644
index 0000000..4585529
--- /dev/null
+++ b/plugin/builtin/starlark/decoder.harbor@v1.star
@@ -0,0 +1,12 @@
+load("encoding/json.star", "json")
+
+def main(input):
+    data = json.decode(input)
+
+    event = data["event_data"]
+
+    output = []
+    for resource in event["resources"]:
+        output.append(resource["resource_url"])
+
+    return output