diff --git a/web/client.lisp b/web/client.lisp
index d93c1cf..3bf9e3e 100644
--- a/web/client.lisp
+++ b/web/client.lisp
@@ -22,7 +22,9 @@
    (doc-path :reader doc-path :initarg :doc-path :initform "/")
    (credentials :reader credentials :initarg :credentials :initform nil)
    (api-path :reader api-path :initarg :api-path :initform "/api/")
-   (accept :reader accept :initarg :accept :initform "text/html")))
+   (accept :reader accept :initarg :accept :initform "text/html")
+   (data-renderer :reader data-renderer :initarg :data-renderer :initform #'urlencoded)
+   ))
 
 ;;;; client context (= service)
 
@@ -35,14 +37,10 @@
 (defun send-message (ctx msg)
   (let* ((cfg (core:config ctx))
          (url (str:concat (base-url cfg) (api-path cfg) (msgpath msg)))
-         (data (shape:data msg))
          (cred (credentials cfg))
-         (params `(
-                   ;:content ,(data-as-json data)
-                   :content ,(data-as-alist data)
-                   :headers (("Accept" . ,(accept cfg)))
-                   :cookie-jar ,*cookie-jar*
-                   )))
+         (params `(:headers (("Accept" . ,(accept cfg)))
+                   :cookie-jar ,*cookie-jar*)))
+    (setf params (funcall (data-renderer cfg) ctx msg params))
     (when cred
       (util:plist-add params :basic-auth (cons (car cred) (cadr cred))))
     (apply #'dex:post url params)
@@ -52,11 +50,16 @@
   (str:join "/" (loop for p in (shape:head msg) 
                       when p collect (string-downcase p))))
 
-(defun data-as-json (data)
-  (if (symbolp (car data))   ; seems to be a property list
-    (let ((ht (alx:plist-hash-table data)))
-      (jzon:stringify ht))
-    data))
+(defun urlencoded (ctx msg params)
+  (util:plist-add params :content (data-as-alist (shape:data msg)))
+  (push '(:content-type . "application/x-www-form-urlencoded") (getf params :headers))
+  params)
+
+(defun json (ctx msg params)
+  (let ((ht (alx:plist-hash-table (shape:data msg))))
+    (util:plist-add params :content (jzon:stringify ht)))
+  (push '(:content-type . "application/json") (getf params :headers))
+  params)
 
 (defun data-as-alist (data)
   (if (symbolp (car data))   ; seems to be a property list