diff --git a/beetsplug/web/__init__.py b/beetsplug/web/__init__.py
index e80c8c29..c8f979fa 100644
--- a/beetsplug/web/__init__.py
+++ b/beetsplug/web/__init__.py
@@ -244,7 +244,9 @@ class QueryConverter(PathConverter):
 
     def to_python(self, value):
         queries = value.split('/')
-        return [query.replace('\\', os.sep) for query in queries]
+        """Do not do path substitution on regex value tests"""
+        return [query if '::' in query else query.replace('\\', os.sep)
+                for query in queries]
 
     def to_url(self, value):
         return ','.join([v.replace(os.sep, '\\') for v in value])
diff --git a/docs/changelog.rst b/docs/changelog.rst
index 929ab8cb..f39c4158 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -206,6 +206,8 @@ Other new things:
 
 Fixes:
 
+* :bug:`/plugins/web`: Allow use of backslash in regex web queries.
+  :bug:`3867`
 * :bug:`/plugins/web`: Fixed a small bug which caused album artpath to be
   redacted even when ``include_paths`` option is set.
   :bug:`3866`
diff --git a/docs/plugins/lyrics.rst b/docs/plugins/lyrics.rst
index b7176404..b4990967 100644
--- a/docs/plugins/lyrics.rst
+++ b/docs/plugins/lyrics.rst
@@ -58,7 +58,7 @@ configuration file. The available options are:
   sources known to be scrapeable.
 - **sources**: List of sources to search for lyrics. An asterisk ``*`` expands
   to all available sources.
-  Default: ``google lyricwiki musixmatch genius``, i.e., all the
+  Default: ``google musixmatch genius``, i.e., all the
   available sources. The ``google`` source will be automatically
   deactivated if no ``google_API_key`` is setup.
   Both it and the ``genius`` source will only be enabled if BeautifulSoup is

diff --git a/test/test_web.py b/test/test_web.py
index 88be3136..606f1e24 100644
--- a/test/test_web.py
+++ b/test/test_web.py
@@ -13,11 +13,22 @@ from test import _common
 from beets.library import Item, Album
 from beetsplug import web
 
+import platform
+
+from beets import logging
+
 
 class WebPluginTest(_common.LibTestCase):
 
     def setUp(self):
+
         super(WebPluginTest, self).setUp()
+        self.log = logging.getLogger('beets.web')
+
+        if platform.system() == 'Windows':
+            self.path_prefix = u'C:'
+        else:
+            self.path_prefix = u''
 
         # Add fixtures
         for track in self.lib.items():
@@ -26,12 +37,30 @@ class WebPluginTest(_common.LibTestCase):
         # Add library elements. Note that self.lib.add overrides any "id=<n>"
         # and assigns the next free id number.
         # The following adds will create items #1, #2 and #3
-        self.lib.add(Item(title=u'title', path='/path_1', album_id=2))
-        self.lib.add(Item(title=u'another title', path='/path_2'))
-        self.lib.add(Item(title=u'and a third'))
+        path1 = self.path_prefix + os.sep + \
+            os.path.join(b'path_1').decode('utf-8')
+        self.lib.add(Item(title=u'title',
+                          path=path1,
+                          album_id=2,
+                          artist='AAA Singers'))
+        path2 = self.path_prefix + os.sep + \
+            os.path.join(b'somewhere', b'a').decode('utf-8')
+        self.lib.add(Item(title=u'another title',
+                          path=path2,
+                          artist='AAA Singers'))
+        path3 = self.path_prefix + os.sep + \
+            os.path.join(b'somewhere', b'abc').decode('utf-8')
+        self.lib.add(Item(title=u'and a third',
+                          testattr='ABC',
+                          path=path3,
+                          album_id=2))
         # The following adds will create albums #1 and #2
-        self.lib.add(Album(album=u'album'))
-        self.lib.add(Album(album=u'other album', artpath='/art_path_2'))
+        self.lib.add(Album(album=u'album',
+                           albumtest='xyz'))
+        path4 = self.path_prefix + os.sep + \
+            os.path.join(b'somewhere2', b'art_path_2').decode('utf-8')
+        self.lib.add(Album(album=u'other album',
+                           artpath=path4))
 
         web.app.config['TESTING'] = True
         web.app.config['lib'] = self.lib
@@ -42,17 +71,25 @@ class WebPluginTest(_common.LibTestCase):
         web.app.config['INCLUDE_PATHS'] = True
         response = self.client.get('/item/1')
         res_json = json.loads(response.data.decode('utf-8'))
+        expected_path = self.path_prefix + os.sep \
+            + os.path.join(b'path_1').decode('utf-8')
 
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(res_json['path'], u'/path_1')
+        self.assertEqual(res_json['path'], expected_path)
+
+        web.app.config['INCLUDE_PATHS'] = False
 
     def test_config_include_artpaths_true(self):
         web.app.config['INCLUDE_PATHS'] = True
         response = self.client.get('/album/2')
         res_json = json.loads(response.data.decode('utf-8'))
+        expected_path = self.path_prefix + os.sep \
+            + os.path.join(b'somewhere2', b'art_path_2').decode('utf-8')
 
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(res_json['artpath'], u'/art_path_2')
+        self.assertEqual(res_json['artpath'], expected_path)
+
+        web.app.config['INCLUDE_PATHS'] = False
 
     def test_config_include_paths_false(self):
         web.app.config['INCLUDE_PATHS'] = False
@@ -91,8 +128,8 @@ class WebPluginTest(_common.LibTestCase):
 
         self.assertEqual(response.status_code, 200)
         self.assertEqual(len(res_json['items']), 2)
-        response_titles = [item['title'] for item in res_json['items']]
-        assertCountEqual(self, response_titles, [u'title', u'another title'])
+        response_titles = {item['title'] for item in res_json['items']}
+        self.assertEqual(response_titles, {u'title', u'another title'})
 
     def test_get_single_item_not_found(self):
         response = self.client.get('/item/4')
@@ -116,6 +153,7 @@ class WebPluginTest(_common.LibTestCase):
         self.assertEqual(response.status_code, 404)
 
     def test_get_item_empty_query(self):
+        """ testing item query: <empty> """
         response = self.client.get('/item/query/')
         res_json = json.loads(response.data.decode('utf-8'))
 
@@ -123,6 +161,7 @@ class WebPluginTest(_common.LibTestCase):
         self.assertEqual(len(res_json['items']), 3)
 
     def test_get_simple_item_query(self):
+        """ testing item query: another """
         response = self.client.get('/item/query/another')
         res_json = json.loads(response.data.decode('utf-8'))
 
@@ -131,6 +170,52 @@ class WebPluginTest(_common.LibTestCase):
         self.assertEqual(res_json['results'][0]['title'],
                          u'another title')
 
+    def test_query_item_string(self):
+        """ testing item query: testattr:ABC """
+        response = self.client.get('/item/query/testattr%3aABC')
+        res_json = json.loads(response.data.decode('utf-8'))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(len(res_json['results']), 1)
+        self.assertEqual(res_json['results'][0]['title'],
+                         u'and a third')
+
+    def test_query_item_regex(self):
+        """ testing item query: testattr::[A-C]+ """
+        response = self.client.get('/item/query/testattr%3a%3a[A-C]%2b')
+        res_json = json.loads(response.data.decode('utf-8'))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(len(res_json['results']), 1)
+        self.assertEqual(res_json['results'][0]['title'],
+                         u'and a third')
+
+    def test_query_item_regex_backslash(self):
+        # """ testing item query: testattr::\w+ """
+        response = self.client.get('/item/query/testattr%3a%3a%5cw%2b')
+        res_json = json.loads(response.data.decode('utf-8'))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(len(res_json['results']), 1)
+        self.assertEqual(res_json['results'][0]['title'],
+                         u'and a third')
+
+    def test_query_item_path(self):
+        # """ testing item query: path:\somewhere\a """
+        """ Note: path queries are special: the query item must match the path
+        from the root all the way to a directory, so this matches 1 item """
+        """ Note: filesystem separators in the query must be '\' """
+
+        response = self.client.get('/item/query/path:'
+                                   + self.path_prefix
+                                   + '\\somewhere\\a')
+        res_json = json.loads(response.data.decode('utf-8'))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(len(res_json['results']), 1)
+        self.assertEqual(res_json['results'][0]['title'],
+                         u'another title')
+
     def test_get_all_albums(self):
         response = self.client.get('/album/')
         res_json = json.loads(response.data.decode('utf-8'))
@@ -177,10 +262,43 @@ class WebPluginTest(_common.LibTestCase):
         res_json = json.loads(response.data.decode('utf-8'))
 
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(len(res_json['items']), 1)
+        self.assertEqual(len(res_json['items']), 2)
         self.assertEqual(res_json['items'][0]['album'],
                          u'other album')
-        self.assertEqual(res_json['items'][0]['id'], 1)
+        self.assertEqual(res_json['items'][1]['album'],
+                         u'other album')
+        response_track_titles = {item['title'] for item in res_json['items']}
+        self.assertEqual(response_track_titles, {u'title', u'and a third'})
+
+    def test_query_album_string(self):
+        """ testing query: albumtest:xy """
+        response = self.client.get('/album/query/albumtest%3axy')
+        res_json = json.loads(response.data.decode('utf-8'))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(len(res_json['results']), 1)
+        self.assertEqual(res_json['results'][0]['album'],
+                         u'album')
+
+    def test_query_album_artpath_regex(self):
+        """ testing query: artpath::art_ """
+        response = self.client.get('/album/query/artpath%3a%3aart_')
+        res_json = json.loads(response.data.decode('utf-8'))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(len(res_json['results']), 1)
+        self.assertEqual(res_json['results'][0]['album'],
+                         u'other album')
+
+    def test_query_album_regex_backslash(self):
+        # """ testing query: albumtest::\w+ """
+        response = self.client.get('/album/query/albumtest%3a%3a%5cw%2b')
+        res_json = json.loads(response.data.decode('utf-8'))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(len(res_json['results']), 1)
+        self.assertEqual(res_json['results'][0]['album'],
+                         u'album')
 
     def test_get_stats(self):
         response = self.client.get('/stats')

web: web page search box doesn't work for regex searches
### Problem

This is not a problem in the web API itself, but in the web pages which provide the simple web user interface.

Bringing up the web interface and entering a query such as ``somefield::.`` never returns any results.
The problem is that the web page ends up double URI encoding the search before passing it to GET /item/query.

I have a fix (in `static/beets.js`) which I can submit once the current PR is done.

However, I have no idea how to create a test for this as it would mean starting the webserver, submitting an HTTP request and checking the resulting (complex) HTML. Does anyone have any example of doing that in the beets pytest environment? I know very little python and nothing about pytest but I may be able to steal a similar test if one exists!

EDIT: Actually, it is the last step - parsing and checking the resulting HTML which is hard (the rest is what the tests already do - but they are dealing with JSON responses, not HTML responses). Does anyone have any tools or examples of checking HTML responses? Or do I just do some simple string searches and hope nothing changes too much to change the page in the future?
test/test_web.py::WebPluginTest::test_query_album_regex_backslash test/test_web.py::WebPluginTest::test_query_item_regex_backslash
test/test_web.py::WebPluginTest::test_config_include_artpaths_false test/test_web.py::WebPluginTest::test_config_include_artpaths_true test/test_web.py::WebPluginTest::test_config_include_paths_false test/test_web.py::WebPluginTest::test_config_include_paths_true test/test_web.py::WebPluginTest::test_get_album_details test/test_web.py::WebPluginTest::test_get_album_empty_query test/test_web.py::WebPluginTest::test_get_all_albums test/test_web.py::WebPluginTest::test_get_all_items test/test_web.py::WebPluginTest::test_get_item_empty_query test/test_web.py::WebPluginTest::test_get_multiple_albums_by_id test/test_web.py::WebPluginTest::test_get_multiple_items_by_id test/test_web.py::WebPluginTest::test_get_simple_album_query test/test_web.py::WebPluginTest::test_get_simple_item_query test/test_web.py::WebPluginTest::test_get_single_album_by_id test/test_web.py::WebPluginTest::test_get_single_item_by_id test/test_web.py::WebPluginTest::test_get_single_item_by_path_not_found_if_not_in_library test/test_web.py::WebPluginTest::test_get_single_item_not_found test/test_web.py::WebPluginTest::test_get_stats test/test_web.py::WebPluginTest::test_query_album_artpath_regex test/test_web.py::WebPluginTest::test_query_album_string test/test_web.py::WebPluginTest::test_query_item_path test/test_web.py::WebPluginTest::test_query_item_regex test/test_web.py::WebPluginTest::test_query_item_string