diff --git a/API.md b/API.md
index d34a083..abf01ee 100644
--- a/API.md
+++ b/API.md
@@ -280,3 +280,63 @@ curl "http://localhost:8080/status?pretty=y"
   ]
 }
 ```
+
+## Filer server
+
+### POST/PUT/Get files
+```bash
+# Basic Usage:
+	//create or overwrite the file, the directories /path/to will be automatically created
+	POST /path/to/file
+	//get the file content
+	GET /path/to/file
+	//create or overwrite the file, the filename in the multipart request will be used
+	POST /path/to/
+	//return a json format subdirectory and files listing
+	GET /path/to/
+```
+Examples:
+```bash
+# Basic Usage:
+> curl -F file=@report.js "http://localhost:8888/javascript/"
+{"name":"report.js","size":866}
+> curl  "http://localhost:8888/javascript/report.js"   # get the file content
+...
+> curl -F file=@report.js "http://localhost:8888/javascript/new_name.js"    # upload the file with a different name
+{"name":"report.js","size":866}
+> curl  "http://localhost:8888/javascript/?pretty=y"            # list all files under /javascript/
+{
+  "Directory": "/javascript/",
+  "Files": [
+    {
+      "name": "new_name.js",
+      "fid": "3,034389657e"
+    },
+    {
+      "name": "report.js",
+      "fid": "7,0254f1f3fd"
+    }
+  ],
+  "Subdirectories": null
+}
+```
+
+### List files under a directory
+This is for embedded filer only.
+
+Some folder can be very large. To efficiently list files, we use a non-traditional way to iterate files. Every pagination you provide a "lastFileName", and a "limit=x". The filer locate the "lastFileName" in O(log(n)) time, and retrieve the next x files.
+
+```bash
+curl  "http://localhost:8888/javascript/?pretty=y&lastFileName=new_name.js&limit=2"
+{
+  "Directory": "/javascript/",
+  "Files": [
+    {
+      "name": "report.js",
+      "fid": "7,0254f1f3fd"
+    }
+  ],
+  "Subdirectories": null
+}
+
+```