diff --git a/conservancy_beancount/rtutil.py b/conservancy_beancount/rtutil.py
new file mode 100644
index 0000000..3bdc2f9
--- /dev/null
+++ b/conservancy_beancount/rtutil.py
@@ -0,0 +1,107 @@
+"""RT client utilities"""
+# Copyright © 2020  Brett Smith
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import functools
+import mimetypes
+import urllib.parse as urlparse
+
+import rt
+
+from typing import (
+    Mapping,
+    Optional,
+    Tuple,
+    Union,
+)
+
+AttachmentTuple = Tuple[str, str, str, str]
+RTId = Union[int, str]
+
+class RT:
+    def __init__(self, rt_client: rt.Rt) -> None:
+        self.rt = rt_client
+        urlparts = urlparse.urlparse(rt_client.url)
+        try:
+            index = urlparts.path.index('/REST/')
+        except ValueError:
+            base_path = urlparts.path.rstrip('/') + '/'
+        else:
+            base_path = urlparts.path[:index + 1]
+        self.url_base = urlparts._replace(path=base_path)
+
+    def _extend_url(self,
+                    path_tail: str,
+                    fragment: Optional[str]=None,
+                    **query: str,
+    ) -> str:
+        if fragment is None:
+            fragment = self.url_base.fragment
+        else:
+            fragment = urlparse.quote(fragment)
+        if query:
+            query_s = urlparse.urlencode(query)
+        else:
+            query_s = self.url_base.query
+        urlparts = self.url_base._replace(
+            path=self.url_base.path + urlparse.quote(path_tail),
+            query=query_s,
+            fragment=fragment,
+        )
+        return urlparse.urlunparse(urlparts)
+
+    def _ticket_url(self, ticket_id: RTId, txn_id: Optional[RTId]=None) -> str:
+        if txn_id is None:
+            fragment = None
+        else:
+            fragment = 'txn-{}'.format(txn_id)
+        return self._extend_url('Ticket/Display.html', fragment, id=str(ticket_id))
+
+    @functools.lru_cache()
+    def attachment_url(self, ticket_id: RTId, attachment_id: RTId) -> Optional[str]:
+        attachment = self.rt.get_attachment(ticket_id, attachment_id)
+        if attachment is None:
+            return None
+        mimetype = attachment.get('ContentType', '')
+        if mimetype.startswith('text/'):
+            return self._ticket_url(ticket_id, attachment['Transaction'])
+        else:
+            filename = attachment.get('Filename', '')
+            if not filename:
+                filename = 'RT{} attachment {}{}'.format(
+                    ticket_id,
+                    attachment_id,
+                    mimetypes.guess_extension(mimetype) or '.bin',
+                )
+            path_tail = 'Ticket/Attachment/{0[Transaction]}/{0[id]}/{1}'.format(
+                attachment,
+                filename,
+            )
+            return self._extend_url(path_tail)
+
+    def exists(self, ticket_id: RTId, attachment_id: Optional[RTId]=None) -> bool:
+        return self.url(ticket_id, attachment_id) is not None
+
+    @functools.lru_cache()
+    def ticket_url(self, ticket_id: RTId) -> Optional[str]:
+        if self.rt.get_ticket(ticket_id) is None:
+            return None
+        return self._ticket_url(ticket_id)
+
+    def url(self, ticket_id: RTId, attachment_id: Optional[RTId]=None) -> Optional[str]:
+        if attachment_id is None:
+            return self.ticket_url(ticket_id)
+        else:
+            return self.attachment_url(ticket_id, attachment_id)
diff --git a/tests/test_rtutil.py b/tests/test_rtutil.py
new file mode 100644
index 0000000..accb7af
--- /dev/null
+++ b/tests/test_rtutil.py
@@ -0,0 +1,99 @@
+"""Test RT integration"""
+# Copyright © 2020  Brett Smith
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import pytest
+
+from . import testutil
+
+from conservancy_beancount import rtutil
+
+DEFAULT_RT_URL = testutil.RTClient.DEFAULT_URL[:-9]
+
+EXPECTED_URLS = [
+    (1, None, 'Ticket/Display.html?id=1'),
+    (1, 2, 'Ticket/Display.html?id=1#txn-1'),
+    (1, 4, 'Ticket/Attachment/1/4/Forwarded%20Message.eml'),
+    (1, 99, None),
+    (2, 1, None),
+    (2, 10, 'Ticket/Attachment/7/10/screenshot.png'),
+    (2, 13, 'Ticket/Display.html?id=2#txn-11'),
+    (2, 14, 'Ticket/Display.html?id=2#txn-11'),  # statement.txt
+    (3, None, 'Ticket/Display.html?id=3'),
+    (9, None, None),
+]
+
+@pytest.fixture
+def rt():
+    client = testutil.RTClient()
+    return rtutil.RT(client)
+
+@pytest.fixture
+def new_client():
+    class RTClient(testutil.RTClient):
+        TICKET_DATA = {'1': [], '2': []}
+    return RTClient()
+
+@pytest.mark.parametrize('ticket_id,attachment_id,expected', EXPECTED_URLS)
+def test_url(rt, ticket_id, attachment_id, expected):
+    if expected is not None:
+        expected = DEFAULT_RT_URL + expected
+    assert rt.url(ticket_id, attachment_id) == expected
+
+@pytest.mark.parametrize('attachment_id', [
+    3,
+    None,
+])
+def test_url_caches(new_client, attachment_id):
+    new_client.TICKET_DATA['1'].append(('3', '(Unnamed)', 'text/plain', '3.0k'))
+    if attachment_id is None:
+        fragment = ''
+    else:
+        fragment = '#txn-3'
+    expected = '{}Ticket/Display.html?id=1{}'.format(DEFAULT_RT_URL, fragment)
+    rt = rtutil.RT(new_client)
+    assert rt.url(1, attachment_id) == expected
+    new_client.TICKET_DATA.clear()
+    assert rt.url(1, attachment_id) == expected
+
+@pytest.mark.parametrize('mimetype,extension', [
+    ('application/pdf', 'pdf'),
+    ('image/png', 'png'),
+    ('message/rfc822', 'eml'),
+    ('x-test/x-unknown', 'bin'),
+])
+def test_url_default_filename(new_client, mimetype, extension):
+    new_client.TICKET_DATA['1'].append(('9', '(Unnamed)', mimetype, '50.5k'))
+    rt = rtutil.RT(new_client)
+    expected = '{}Ticket/Attachment/9/9/RT1%20attachment%209.{}'.format(DEFAULT_RT_URL, extension)
+    assert rt.url(1, 9) == expected
+
+@pytest.mark.parametrize('ticket_id,attachment_id,expected', EXPECTED_URLS)
+def test_exists(rt, ticket_id, attachment_id, expected):
+    expected = False if expected is None else True
+    assert rt.exists(ticket_id, attachment_id) is expected
+
+def test_exists_caches(new_client):
+    new_client.TICKET_DATA['1'].append(('3', '(Unnamed)', 'text/plain', '3.0k'))
+    rt = rtutil.RT(new_client)
+    assert rt.exists(1, 3)
+    assert rt.exists(2)
+    assert not rt.exists(1, 9)
+    assert not rt.exists(9)
+    new_client.TICKET_DATA.clear()
+    assert rt.exists(1, 3)
+    assert rt.exists(2)
+    assert not rt.exists(1, 9)
+    assert not rt.exists(9)
diff --git a/tests/testutil.py b/tests/testutil.py
index bb30ffd..c85e901 100644
--- a/tests/testutil.py
+++ b/tests/testutil.py
@@ -15,6 +15,7 @@
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 import datetime
+import itertools
 
 import beancount.core.amount as bc_amount
 import beancount.core.data as bc_data
@@ -114,9 +115,54 @@ class TestConfig:
         return self.repo_path
 
 
+class _TicketBuilder:
+    MESSAGE_ATTACHMENTS = [
+        ('(Unnamed)', 'multipart/alternative', '0b'),
+        ('(Unnamed)', 'text/plain', '1.2k'),
+        ('(Unnamed)', 'text/html', '1.4k'),
+    ]
+    MISC_ATTACHMENTS = [
+        ('Forwarded Message.eml', 'message/rfc822', '3.1k'),
+        ('photo.jpg', 'image/jpeg', '65.2k'),
+        ('document.pdf', 'application/pdf', '326k'),
+        ('screenshot.png', 'image/png', '1.9m'),
+        ('statement.txt', 'text/plain', '652b'),
+    ]
+
+    def __init__(self):
+        self.id_seq = itertools.count(1)
+        self.misc_attchs = itertools.cycle(self.MISC_ATTACHMENTS)
+
+    def new_attch(self, attch):
+        return (str(next(self.id_seq)), *attch)
+
+    def new_msg_with_attachments(self, attachments_count=1):
+        for attch in self.MESSAGE_ATTACHMENTS:
+            yield self.new_attch(attch)
+        for _ in range(attachments_count):
+            yield self.new_attch(next(self.misc_attchs))
+
+    def new_messages(self, messages_count, attachments_count=None):
+        for n in range(messages_count):
+            if attachments_count is None:
+                att_count = messages_count - n
+            else:
+                att_count = attachments_count
+            yield from self.new_msg_with_attachments(att_count)
+
+
 class RTClient:
+    _builder = _TicketBuilder()
+    DEFAULT_URL = 'https://example.org/defaultrt/REST/1.0/'
+    TICKET_DATA = {
+        '1': list(_builder.new_messages(1, 3)),
+        '2': list(_builder.new_messages(2, 1)),
+        '3': list(_builder.new_messages(3, 0)),
+    }
+    del _builder
+
     def __init__(self,
-                 url,
+                 url=DEFAULT_URL,
                  default_login=None,
                  default_password=None,
                  proxy=None,
@@ -145,3 +191,44 @@ class RTClient:
         self.login_result = bool(login and password and not password.startswith('bad'))
         self.last_login = (login, password, self.login_result)
         return self.login_result
+
+    def get_attachments(self, ticket_id):
+        try:
+            return list(self.TICKET_DATA[str(ticket_id)])
+        except KeyError:
+            return None
+
+    def get_attachment(self, ticket_id, attachment_id):
+        try:
+            att_seq = iter(self.TICKET_DATA[str(ticket_id)])
+        except KeyError:
+            None
+        att_id = str(attachment_id)
+        multipart_id = None
+        for attch in att_seq:
+            if attch[0] == att_id:
+                break
+            elif attch[2].startswith('multipart/'):
+                multipart_id = attch[0]
+        else:
+            return None
+        tx_id = multipart_id or att_id
+        if attch[1] == '(Unnamed)':
+            filename = ''
+        else:
+            filename = attch[1]
+        return {
+            'id': att_id,
+            'ContentType': attch[2],
+            'Filename': filename,
+            'Transaction': tx_id,
+        }
+
+    def get_ticket(self, ticket_id):
+        ticket_id_s = str(ticket_id)
+        if ticket_id_s not in self.TICKET_DATA:
+            return None
+        return {
+            'id': 'ticket/{}'.format(ticket_id_s),
+            'numerical_id': ticket_id_s,
+        }