diff --git a/pkg/client/requests.go b/pkg/client/requests.go
index 6ce9fa5..d664771 100644
--- a/pkg/client/requests.go
+++ b/pkg/client/requests.go
@@ -88,7 +88,7 @@ func (c *Client) microsubPostRequest(action string, args map[string]string) (*ht
 
 	if res.StatusCode != 200 {
 		msg, _ := ioutil.ReadAll(res.Body)
-		return nil, fmt.Errorf("unsuccessful response: %d: %q", res.StatusCode, string(msg))
+		return nil, fmt.Errorf("unsuccessful response: %d: %q", res.StatusCode, strings.TrimSpace(string(msg)))
 	}
 
 	return res, err
@@ -116,7 +116,7 @@ func (c *Client) microsubPostFormRequest(action string, args map[string]string,
 
 	if res.StatusCode != 200 {
 		msg, _ := ioutil.ReadAll(res.Body)
-		return nil, fmt.Errorf("unsuccessful response: %d: %q", res.StatusCode, string(msg))
+		return nil, fmt.Errorf("unsuccessful response: %d: %q", res.StatusCode, strings.TrimSpace(string(msg)))
 	}
 
 	return res, err
@@ -180,7 +180,7 @@ func (c *Client) TimelineGet(before, after, channel string) (microsub.Timeline,
 func (c *Client) PreviewURL(url string) (microsub.Timeline, error) {
 	args := make(map[string]string)
 	args["url"] = url
-	res, err := c.microsubGetRequest("preview", args)
+	res, err := c.microsubPostRequest("preview", args)
 	if err != nil {
 		return microsub.Timeline{}, err
 	}
diff --git a/pkg/server/microsub.go b/pkg/server/microsub.go
index d3b749d..227ff76 100644
--- a/pkg/server/microsub.go
+++ b/pkg/server/microsub.go
@@ -125,7 +125,7 @@ func (h *microsubHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 				http.Error(w, "internal server error", 500)
 			}
 		} else {
-			http.Error(w, fmt.Sprintf("unknown action %s\n", action), 400)
+			http.Error(w, fmt.Sprintf("unknown action %s", action), 400)
 			return
 		}
 		return
@@ -182,6 +182,13 @@ func (h *microsubHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 				return
 			}
 			respondJSON(w, []string{})
+		} else if action == "preview" {
+			timeline, err := h.backend.PreviewURL(values.Get("url"))
+			if err != nil {
+				http.Error(w, err.Error(), 500)
+				return
+			}
+			respondJSON(w, timeline)
 		} else if action == "search" {
 			query := values.Get("query")
 			channel := values.Get("channel")