diff --git a/Filer-Server-API.md b/Filer-Server-API.md
index 6dff6f1..4894640 100644
--- a/Filer-Server-API.md
+++ b/Filer-Server-API.md
@@ -8,10 +8,15 @@ You can append to any HTTP API with &pretty=y to see a formatted json output.
 # Basic Usage:
 	//create or overwrite the file, the directories /path/to will be automatically created
 	POST /path/to/file
+	PUT /path/to/file
+	//create or append the file
+	POST /path/to/file?op=append
+	PUT /path/to/file?op=append
 	//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/
+	PUT /path/to/
 	//return a json format subdirectory and files listing
 	GET /path/to/
         Accept: application/json
@@ -32,6 +37,7 @@ You can append to any HTTP API with &pretty=y to see a formatted json output.
 | ttl | time to live, examples, 3m: 3 minutes, 4h: 4 hours, 5d: 5 days, 6w: 6 weeks, 7M: 7 months, 8y: 8 years | empty |
 | maxMB | max chunk size | empty |
 | mode | file mode | 0660 |
+| op | file operation, currently only support "append" | empty |
 | header: `Content-Type` | used for auto compression | empty |
 | prefixed header: `Seaweed-` | example: `Seaweed-name1: value1`. Returned as `Seaweed-Name1: value1` in GET/HEAD response header. | empty |
 
@@ -46,9 +52,15 @@ Examples:
 {"name":"report.js","size":866,"fid":"7,0254f1f3fd","url":"http://localhost:8081/7,0254f1f3fd"}
 > 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 (The local report.js becomes new_name.js on the server side.)
-> curl  http://localhost:8888/test.yaml --upload-file test.yaml  # upload file by PUT
-{"name":"report.js","size":866,"fid":"3,034389657e","url":"http://localhost:8081/3,034389657e"}
+> curl -F file=@report.js "http://localhost:8888/javascript/new_name.js"    # upload the file to a different name
+{"name":"report.js","size":5514}
+> curl -T test.yaml http://localhost:8888/test.yaml                         # upload file by PUT
+{"name":"test.yaml","size":866}
+> curl -F file=@report.js "http://localhost:8888/javascript/new_name.js?op=append"    # append to an file
+{"name":"report.js","size":5514}
+> curl -T test.yaml http://localhost:8888/test.yaml?op=append                         # append to an file by PUT
+{"name":"test.yaml","size":866}
+
 > curl -H "Accept: application/json" "http://localhost:8888/javascript/?pretty=y"            # list all files under /javascript/
 curl -H "Accept: application/json" "http://localhost:8888/javascript/?pretty=y"
 {