diff --git a/doc/source/main/tools.rst b/doc/source/main/tools.rst
index 596f4bf..764c715 100644
--- a/doc/source/main/tools.rst
+++ b/doc/source/main/tools.rst
@@ -393,3 +393,47 @@ Call command line and capture output line by line.
     21/06/2021 22:34:42 - DEBUG - drwxr-xr-x 13 mau mau 4.0K Jun 21 15:34 Projects
     21/06/2021 22:34:42 - DEBUG - drwxr-xr-x  2 mau mau 4.0K May 11 18:48 Templates
     21/06/2021 22:34:42 - DEBUG - drwxr-xr-x  2 mau mau 4.0K Jun 20 23:27 Videos
+
+
+Timer
+^^^^^
+
+Execute any macro every seconds.
+
+.. code-block:: python
+
+    TIMER_NAME = 'clock'
+
+    def show_time():
+        app.debug(app.now(True))
+        return
+
+    def start_clock():
+        seconds = 1
+        macro = {
+            'library': 'test',
+            'name': 'show_time',
+        }
+        app.start_timer(TIMER_NAME, seconds, macro)
+        return
+
+    def stop_clock():
+        app.stop_timer(TIMER_NAME)
+        return
+
+    def main(args=None):
+        start_clock()
+        return
+
+Execute `stop_clock` for stop timer.
+
+.. code-block:: bash
+
+    21/06/2021 22:43:17 - INFO - Timer started... show_time
+    21/06/2021 22:43:18 - DEBUG - 22:43:18.080315
+    21/06/2021 22:43:19 - DEBUG - 22:43:19.082211
+    ...
+    21/06/2021 22:43:46 - DEBUG - 22:43:46.126446
+    21/06/2021 22:43:47 - DEBUG - 22:43:47.128487
+    21/06/2021 22:43:47 - INFO - Timer stopped... show_time
+