Where is the "file manager"? Can you help me!!!

Dear,
I use web server to send "*.bin" file, and use "post handler" to receive data.
...
$.ajax({\
url: '/echo',
type: 'POST',
data: data
...

httpd_uri_t echo = {
.uri = "/echo",
.method = HTTP_POST,
.handler = echo_post_handler,
.user_ctx = NULL
};
The app runs well when the size of bin ...