diff --git a/IPython/html/nbconvert/handlers.py b/IPython/html/nbconvert/handlers.py
index 1cb9ba954..fb97f5f03 100644
--- a/IPython/html/nbconvert/handlers.py
+++ b/IPython/html/nbconvert/handlers.py
@@ -7,11 +7,8 @@ from tornado import web
 from ..base.handlers import IPythonHandler, notebook_path_regex
 from IPython.nbformat.current import to_notebook_json
 
-from IPython.utils import tz
 from IPython.utils.py3compat import cast_bytes
 
-import sys
-
 def find_resource_files(output_files_dir):
     files = []
     for dirpath, dirnames, filenames in os.walk(output_files_dir):
@@ -137,4 +134,4 @@ default_handlers = [
     (r"/nbconvert/%s%s" % (_format_regex, notebook_path_regex),
          NbconvertFileHandler),
     (r"/nbconvert/%s" % _format_regex, NbconvertPostHandler),
-]
\ No newline at end of file
+]
diff --git a/IPython/html/services/kernels/kernelmanager.py b/IPython/html/services/kernels/kernelmanager.py
index 5ff0751c5..ff27b5936 100644
--- a/IPython/html/services/kernels/kernelmanager.py
+++ b/IPython/html/services/kernels/kernelmanager.py
@@ -21,9 +21,7 @@ import os
 from tornado import web
 
 from IPython.kernel.multikernelmanager import MultiKernelManager
-from IPython.utils.traitlets import (
-    Dict, List, Unicode,
-)
+from IPython.utils.traitlets import List, Unicode, TraitError
 
 from IPython.html.utils import to_os_path
 from IPython.utils.py3compat import getcwd
diff --git a/IPython/html/services/kernels/tests/test_kernels_api.py b/IPython/html/services/kernels/tests/test_kernels_api.py
index 52b6cf291..5e624a73c 100644
--- a/IPython/html/services/kernels/tests/test_kernels_api.py
+++ b/IPython/html/services/kernels/tests/test_kernels_api.py
@@ -1,10 +1,6 @@
 """Test the kernels service API."""
 
 
-import os
-import sys
-import json
-
 import requests
 
 from IPython.html.utils import url_path_join
diff --git a/IPython/html/tree/handlers.py b/IPython/html/tree/handlers.py
index e5adf03db..b58fe6720 100644
--- a/IPython/html/tree/handlers.py
+++ b/IPython/html/tree/handlers.py
@@ -15,11 +15,9 @@ Authors:
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
-import os
-
 from tornado import web
 from ..base.handlers import IPythonHandler, notebook_path_regex, path_regex
-from ..utils import url_path_join, path2url, url2path, url_escape, is_hidden
+from ..utils import url_path_join, url_escape
 
 #-----------------------------------------------------------------------------
 # Handlers