diff --git a/features/autolink_constants.py b/features/autolink_constants.py
new file mode 100644
index 0000000..ddb9bb3
--- /dev/null
+++ b/features/autolink_constants.py
@@ -0,0 +1,58 @@
+# Copyright 2017 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+"""Some constants of regexes used in Monorail to validate urls and emails."""
+from __future__ import print_function
+from __future__ import division
+from __future__ import absolute_import
+
+import re
+import settings
+
+# We linkify http, https, ftp, and mailto schemes only.
+LINKIFY_SCHEMES = r'https?://|ftp://|mailto:'
+
+# This regex matches shorthand URLs that we know are valid.
+# Example: go/monorail
+# The scheme is optional, and if it is missing we add it to the link.
+IS_A_SHORT_LINK_RE = re.compile(
+    r'(?<![-/._])\b(%s)?'     # Scheme is optional for short links.
+    r'(%s)'        # The list of know shorthand links from settings.py
+    r'/([^\s<]+)'  # Allow anything, checked with validation code.
+    % (LINKIFY_SCHEMES, '|'.join(settings.autolink_shorthand_hosts)),
+    re.UNICODE)
+IS_A_NUMERIC_SHORT_LINK_RE = re.compile(
+    r'(?<![-/._])\b(%s)?'     # Scheme is optional for short links.
+    r'(%s)'        # The list of know shorthand links from settings.py
+    r'/([0-9]+)'  # Allow digits only for these domains.
+    % (LINKIFY_SCHEMES, '|'.join(settings.autolink_numeric_shorthand_hosts)),
+    re.UNICODE)
+
+# This regex matches fully-formed URLs, starting with a scheme.
+# Example: http://chromium.org or mailto:user@example.com
+# We link to the specified URL without adding anything.
+# Also count a start-tag '<' as a url delimeter, since the autolinker
+# is sometimes run against html fragments.
+IS_A_LINK_RE = re.compile(
+    r'\b(%s)'    # Scheme must be a whole word.
+    r'([^\s<]+)' # Allow anything, checked with validation code.
+    % LINKIFY_SCHEMES, re.UNICODE)
+
+# This regex matches text that looks like a URL despite lacking a scheme.
+# Example: crrev.com
+# Since the scheme is not specified, we prepend "http://".
+IS_IMPLIED_LINK_RE = re.compile(
+    r'(?<![-/._])\b[a-z]((-|\.)?[a-z0-9])+\.(com|net|org|edu)\b'  # Domain.
+    r'(/[^\s<]*)?',  # Allow anything, check with validation code.
+    re.UNICODE)
+
+# This regex matches text that looks like an email address.
+# Example: user@example.com
+# These get linked to the user profile page if it exists, otherwise
+# they become a mailto:.
+IS_IMPLIED_EMAIL_RE = re.compile(
+    r'\b[a-z]((-|\.)?[a-z0-9])+@'  # Username@
+    r'[a-z]((-|\.)?[a-z0-9])+\.(com|net|org|edu)\b',  # Domain
+    re.UNICODE)