diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 00000000..97553688
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,4 @@
+# Contributing
+
+Send PR against `dev` branch, not `master`.
+For DNS API see [DNS API Dev Guide](https://github.com/acmesh-official/acme.sh/wiki/DNS-API-Dev-Guide)