diff --git a/nyxt.asd b/nyxt.asd
index abe929211ef..4a4ec77de6d 100644
--- a/nyxt.asd
+++ b/nyxt.asd
@@ -357,7 +357,15 @@ A naive benchmark on a 16 Mpbs bandwidth gives us
                cl-gobject-introspection
                bordeaux-threads)
   :pathname "source/"
-  :components ((:file "renderer/gi-gtk")))
+  :components ((:file "renderer/gi-gtk"))
+  :in-order-to ((test-op (test-op "nyxt/gi-gtk/tests"))))
+
+(defsystem "nyxt/gi-gtk/tests"
+  :depends-on (nyxt/gi-gtk prove)
+  :components ((:file "tests/renderer-package"))
+  :perform (test-op (op c)
+                    (nyxt-run-test c "tests/renderer-offline/")
+                    (nyxt-run-test c "tests/renderer-online/" :network-needed-p t)))
 
 (defsystem "nyxt/qt"
   :depends-on (nyxt
diff --git a/source/browser.lisp b/source/browser.lisp
index ea80697fbe8..3f19be3bb49 100644
--- a/source/browser.lisp
+++ b/source/browser.lisp
@@ -150,8 +150,8 @@ The possible values are `:always-ask', `:always-restore' and `:never-restore'.")
    (before-exit-hook
     (make-instance 'hooks:hook-void)
     :type hooks:hook-void
-    :documentation "Hook run before both `*browser*' and the
-renderer get terminated.  The handlers take no argument.")
+    :documentation "Hook run before both `*browser*' and the renderer get terminated.
+The handlers take no argument.")
    (window-make-hook
     (make-instance 'hook-window)
     :type hook-window
@@ -177,6 +177,11 @@ The handlers take the buffer as argument.")
     :type hook-prompt-buffer
     :documentation "Hook run after the `prompt-buffer'
 class is instantiated and before initializing the prompt-buffer modes.
+The handlers take the prompt-buffer as argument.")
+   (prompt-buffer-ready-hook
+    (make-instance 'hook-prompt-buffer)
+    :type hook-prompt-buffer
+    :documentation "A hook one can attach to waiting for the prompt buffer to be available.
 The handlers take the prompt-buffer as argument.")
    (before-download-hook
     (make-instance 'hook-download)
@@ -363,6 +368,7 @@ restored."
       (restore-session)
       (load-start-urls urls)
       (ffi-buffer-delete dummy))
+    (hooks:run-hook *after-startup-hook*)
     (funcall* (startup-error-reporter-function *browser*))))
 
 ;; Catch a common case for a better error message.
diff --git a/source/configuration.lisp b/source/configuration.lisp
index 149ce54b1f7..78e972220fa 100644
--- a/source/configuration.lisp
+++ b/source/configuration.lisp
@@ -357,3 +357,39 @@ exists."
 
 (defun ensure-file-exists (pathname)
   (open pathname :direction :probe :if-does-not-exist :create))
+
+(export-always 'on)
+(defmacro on (hook args &body body)
+  "Attach a handler with ARGS and BODY to the HOOK.
+
+ARGS can be
+- A symbol if there's only one argument to the callback.
+- A list of arguments.
+- An empty list, if the hook is void."
+  (let ((handler-name (gensym "on-hook-handler"))
+        (args (alex:ensure-list args)))
+    `(hooks:add-hook
+      ,hook (make-instance 'hooks:handler
+                           :fn (lambda ,args
+                                 (declare (ignorable ,@args))
+                                 ,@body)
+                           :name (quote ,handler-name)))))
+
+(export-always 'once-on)
+(defmacro once-on (hook args &body body)
+  "Attach a handler with ARGS and BODY to the HOOK.
+
+Remove the handler after it fires the first time.
+
+See `on'."
+  (let ((handler-name (gensym "once-on-hook-handler"))
+        (args (alex:ensure-list args)))
+    (alex:once-only (hook)
+      `(hooks:add-hook
+        ,hook (make-instance 'hooks:handler
+                             :fn (lambda ,args
+                                   (declare (ignorable ,@args))
+                                   (unwind-protect
+                                        (progn ,@body)
+                                     (hooks:remove-hook ,hook (quote ,handler-name))))
+                             :name (quote ,handler-name))))))
diff --git a/source/global.lisp b/source/global.lisp
index 3184f3e7201..9a3c7dbd58e 100644
--- a/source/global.lisp
+++ b/source/global.lisp
@@ -13,6 +13,10 @@
 This is useful when the browser is run from a REPL so that quitting does not
 close the connection.")
 
+(defvar *headless-p* nil
+  "If non-nil, don't display anything.
+This is convenient for testing purposes or to drive Nyxt programmatically.")
+
 (export-always '*browser*)
 (defvar *browser* nil
   "The entry-point object to a complete instance of Nyxt.
@@ -23,7 +27,7 @@ It can be initialized with
 It's possible to run multiple interfaces of Nyxt at the same time.  You can
 let-bind *browser* to temporarily switch interface.")
 
-(declaim (type hooks:hook-void *after-init-hook*))
+(declaim (type hooks:hook-void *after-init-hook* *after-startup-hook*))
 (export-always '*after-init-hook*)
 (defvar *after-init-hook* (make-instance 'hooks:hook-void)
   "The entry-point object to configure everything in Nyxt.
@@ -36,6 +40,11 @@ A handler can be added with:
 
   (hooks:add-hook *after-init-hook* 'my-foo-function)")
 
+(export-always '*after-startup-hook*)
+(defvar *after-startup-hook* (make-instance 'hooks:hook-void)
+  "Hook run when the browser is started and ready for interaction.
+The handlers take no argument.")
+
 (export-always '*swank-port*)
 (defvar *swank-port* 4006
   "The port that Swank will open a new server on (default Emacs SLIME port
diff --git a/source/prompt-buffer.lisp b/source/prompt-buffer.lisp
index 65df4799910..7fa318bdbce 100644
--- a/source/prompt-buffer.lisp
+++ b/source/prompt-buffer.lisp
@@ -185,6 +185,7 @@ See also `hide-prompt-buffer'."
   ;; TODO: Add method that returns if there is only 1 source with no filter.
   (when prompt-buffer
     (push prompt-buffer (active-prompt-buffers (window prompt-buffer)))
+    (hooks:run-hook (prompt-buffer-ready-hook *browser*) prompt-buffer)
     (prompt-render prompt-buffer)
     (run-thread "Show prompt watcher"
       (let ((prompt-buffer prompt-buffer))
diff --git a/source/renderer/gtk.lisp b/source/renderer/gtk.lisp
index af308c63d5e..df35e07e5aa 100644
--- a/source/renderer/gtk.lisp
+++ b/source/renderer/gtk.lisp
@@ -368,7 +368,8 @@ response.  The BODY is wrapped with `with-protect'."
 
        (gtk:gtk-container-add gtk-object root-box-layout)
        (setf (slot-value *browser* 'last-active-window) window)
-       (gtk:gtk-widget-show-all gtk-object)
+       (unless *headless-p*
+         (gtk:gtk-widget-show-all gtk-object))
        (connect-signal window "key_press_event" nil (widget event)
          (declare (ignore widget))
          #+darwin
@@ -1058,7 +1059,8 @@ See `gtk-browser's `modifier-translator' slot."
   (let ((old-buffer (active-buffer window)))
     (gtk:gtk-container-remove (main-buffer-container window) (gtk-object old-buffer))
     (gtk:gtk-box-pack-start (main-buffer-container window) (gtk-object buffer) :expand t :fill t)
-    (gtk:gtk-widget-show (gtk-object buffer))
+    (unless *headless-p*
+      (gtk:gtk-widget-show (gtk-object buffer)))
     (when focus
       (gtk:gtk-widget-grab-focus (gtk-object buffer)))
     (nyxt/web-extensions::tabs-on-activated old-buffer buffer)
@@ -1076,7 +1078,8 @@ See `gtk-browser's `modifier-translator' slot."
             (push buffer (panel-buffers-right window))))
   (setf (gtk:gtk-widget-size-request (gtk-object buffer))
         (list (width buffer) -1))
-  (gtk:gtk-widget-show (gtk-object buffer)))
+  (unless *headless-p*
+    (gtk:gtk-widget-show (gtk-object buffer))))
 
 (define-ffi-method ffi-window-set-panel-buffer-width ((window gtk-window) (buffer panel-buffer) width)
   "Set the width of a panel buffer."
diff --git a/source/window.lisp b/source/window.lisp
index a9265cacf6a..a114f55858e 100644
--- a/source/window.lisp
+++ b/source/window.lisp
@@ -34,6 +34,7 @@ It's a function of the window argument that returns the title as a string.")
     :export nil
     :type boolean
     :documentation "Whether the window is displayed in fullscreen.")
+   ;; TODO: each frame should have a status buffer, not each window
    (status-buffer
     :export nil)
    (message-buffer-height
diff --git a/tests/renderer-online/set-url.lisp b/tests/renderer-online/set-url.lisp
new file mode 100644
index 00000000000..8e3e8c37775
--- /dev/null
+++ b/tests/renderer-online/set-url.lisp
@@ -0,0 +1,55 @@
+;;;; SPDX-FileCopyrightText: Atlas Engineer LLC
+;;;; SPDX-License-Identifier: BSD-3-Clause
+
+(in-package :nyxt/tests/renderer)
+
+(plan nil)
+
+(class-star:define-class nyxt-user::test-data-profile (nyxt:data-profile)
+  ((nyxt:name :initform "test"))
+  (:documentation "Test profile."))
+
+(defmethod nyxt:expand-data-path ((profile nyxt-user::test-data-profile) (path nyxt:data-path))
+  "Don't persist data"
+  nil)
+
+(defmacro with-prompt-buffer-test (command &body body)
+  (alexandria:with-gensyms (thread)
+    `(let ((,thread (bt:make-thread (lambda () ,command))))
+       (calispel:? (prompt-buffer-channel (current-window)))
+       ,@body
+       (return-selection)
+       (bt:join-thread ,thread))))
+
+;; TODO: Use `with-prompt-buffer-test'.
+;; (with-prompt-buffer-test (set-url)
+;;   (update-prompt-input (current-prompt-buffer) "foobar"))
+
+(subtest "set-url"
+  (let ((url-channel (nyxt::make-channel 1))
+        (url "http://example.org/"))
+    (setf nyxt::*headless-p* t)
+    (on nyxt:*after-startup-hook* ()
+      (let ((buffer-loaded-channel (nyxt::make-channel 1)))
+        (once-on (buffer-loaded-hook (current-buffer)) buffer
+          (calispel:! buffer-loaded-channel t))
+        (let ((thread (run-thread "run set-url"
+                        (calispel:? buffer-loaded-channel 10)
+                        (nyxt:set-url))))
+          (declare (ignorable thread))
+          (on (prompt-buffer-ready-hook *browser*)
+              (prompt-buffer)
+            (sleep 1)
+            (nyxt::set-prompt-buffer-input url prompt-buffer)
+            (prompter:all-ready-p prompt-buffer)
+            (nyxt/prompt-buffer-mode:return-selection prompt-buffer)
+            (once-on (buffer-loaded-hook (current-buffer)) buffer
+              (calispel:! url-channel (nyxt:render-url (nyxt:url buffer)))))
+          ;; (bt:join-thread thread) ; TODO: Make sure thread always returns.
+          )))
+    (nyxt:start :no-init t :no-auto-config t
+                :socket "/tmp/nyxt-test.socket"
+                :data-profile "test")
+    (prove:is (calispel:? url-channel 10) url)))
+
+(finalize)
diff --git a/tests/renderer-package.lisp b/tests/renderer-package.lisp
new file mode 100644
index 00000000000..d74f9e1de5c
--- /dev/null
+++ b/tests/renderer-package.lisp
@@ -0,0 +1,8 @@
+;;;; SPDX-FileCopyrightText: Atlas Engineer LLC
+;;;; SPDX-License-Identifier: BSD-3-Clause
+
+(uiop:define-package nyxt/tests/renderer
+  (:use #:common-lisp)
+  (:use #:nyxt)
+  (:use #:prove)
+  (:import-from #:class-star #:define-class))