diff --git a/docs/CONTRIBUTING.md b/docs/CONTRIBUTING.md
index 25332674..c67db3b1 100644
--- a/docs/CONTRIBUTING.md
+++ b/docs/CONTRIBUTING.md
@@ -21,6 +21,7 @@ Developing
 - [Python 2.7](https://www.python.org)
 - [jq](https://stedolan.github.io/jq/)
 - [curl](https://curl.haxx.se/)
+- [npm](https://www.npmjs.com/) (version 3.10)
 
 ```sh
 pip install -r requirements.txt