diff --git a/.changeset/thirty-baboons-clean.md b/.changeset/thirty-baboons-clean.md
new file mode 100644
index 0000000..e16dc76
--- /dev/null
+++ b/.changeset/thirty-baboons-clean.md
@@ -0,0 +1,5 @@
+---
+"classcharts-api": patch
+---
+
+Declare no side effects
diff --git a/package.json b/package.json
index f956301..ee6b589 100644
--- a/package.json
+++ b/package.json
@@ -60,5 +60,6 @@
   ],
   "engines": {
     "node": ">=18"
-  }
+  },
+  "sideEffects": false
 }