diff --git a/README.md b/README.md
index 9186972..1d287c4 100644
--- a/README.md
+++ b/README.md
@@ -25,15 +25,26 @@ pip install -r requirements.txt
 python configure.py
 ```
 
-`configure.py` prompts for `api_id`, `api_hash`, phone, and group IDs.
+`configure.py` prompts for `api_id`, `api_hash`, phone, and group IDs. The stored
+group IDs remain available to commands that use configured defaults, such as
+`compare.py`.
 
-7. Crawl configured groups:
+7. Crawl one or more groups by ID:
 
 ```bash
-python crawl.py
+python crawl.py <group_id> [<group_id> ...]
 ```
 
-The first crawl asks for the Telegram login code once, then stores the session in Redis. Any later run — on any device pointed at the same Redis — reuses the Redis config and session, and **does not** prompt again.
+For example:
+
+```bash
+python crawl.py -1001234567890 -1009876543210
+```
+
+Only the group IDs supplied to this command are crawled; the stored group list
+is not used. The first crawl asks for the Telegram login code once, then stores
+the session in Redis. Any later run — on any device pointed at the same Redis —
+reuses the Redis config and session, and **does not** prompt again.
 
 ## Compare two crawls
 
diff --git a/crawl.py b/crawl.py
index 6dacf17..51750ac 100644
--- a/crawl.py
+++ b/crawl.py
@@ -1,3 +1,4 @@
+import argparse
 import getpass
 
 from telethon.errors import SessionPasswordNeededError
@@ -10,11 +11,25 @@ from config import load_app_config
 from session_store import load_session, save_session
 
 
-def main():
+def parse_args(argv=None):
+    parser = argparse.ArgumentParser(
+        description='Export members from one or more Telegram groups.',
+    )
+    parser.add_argument(
+        'group_ids',
+        nargs='+',
+        type=int,
+        metavar='group_id',
+        help='Telegram group ID to crawl (provide one or more)',
+    )
+    return parser.parse_args(argv)
+
+
+def main(argv=None):
+    args = parse_args(argv)
     app_config = load_app_config()
     api_hash = app_config['api_hash']
     api_id = app_config['api_id']
-    group_ids = app_config['group_ids']
     phone = app_config['phone']
 
     # Session loads from Redis: a saved string means no re-login on any device.
@@ -32,7 +47,7 @@ def main():
 
     run_time = new_run_time()
     saved = 0
-    for group_id in group_ids:
+    for group_id in args.group_ids:
         try:
             entity = client.get_entity(group_id)
             if not isinstance(entity, (Chat, Channel)):
diff --git a/tests/test_crawl.py b/tests/test_crawl.py
new file mode 100644
index 0000000..438b9ad
--- /dev/null
+++ b/tests/test_crawl.py
@@ -0,0 +1,98 @@
+import os
+import unittest
+from unittest.mock import MagicMock, call, patch
+
+os.environ.setdefault('REDIS_URL', 'redis://localhost')
+
+import crawl
+
+
+class FakeChat:
+    def __init__(self, group_id):
+        self.id = group_id
+        self.title = f'Group {group_id}'
+
+
+class FakeMember:
+    def __init__(self, member_id):
+        self.id = member_id
+
+
+class CrawlArgumentsTest(unittest.TestCase):
+    def test_accepts_multiple_group_ids(self):
+        args = crawl.parse_args(['-100123', '-100456'])
+
+        self.assertEqual(args.group_ids, [-100123, -100456])
+
+    def test_requires_at_least_one_group_id(self):
+        with (
+            patch.object(crawl, 'load_app_config') as load_app_config,
+            patch.object(crawl, 'TelegramClient') as telegram_client,
+            self.assertRaises(SystemExit),
+        ):
+            crawl.main([])
+
+        load_app_config.assert_not_called()
+        telegram_client.assert_not_called()
+
+    def test_rejects_non_integer_group_id(self):
+        with (
+            patch.object(crawl, 'load_app_config') as load_app_config,
+            patch.object(crawl, 'TelegramClient') as telegram_client,
+            self.assertRaises(SystemExit),
+        ):
+            crawl.main(['not-a-group'])
+
+        load_app_config.assert_not_called()
+        telegram_client.assert_not_called()
+
+
+class CrawlMainTest(unittest.TestCase):
+    @patch.object(crawl, 'save_group_export')
+    @patch.object(crawl, 'save_session')
+    @patch.object(crawl, 'load_session', return_value='stored-session')
+    @patch.object(crawl, 'load_app_config')
+    @patch.object(crawl, 'TelegramClient')
+    def test_crawls_supplied_ids_instead_of_configured_ids(
+        self,
+        telegram_client,
+        load_app_config,
+        load_session,
+        save_session,
+        save_group_export,
+    ):
+        load_app_config.return_value = {
+            'api_id': 123,
+            'api_hash': 'hash',
+            'phone': '+15551234567',
+            'group_ids': [999],
+        }
+        client = MagicMock()
+        telegram_client.return_value = client
+        client.is_user_authorized.return_value = True
+        client.session.save.return_value = 'updated-session'
+        client.get_entity.side_effect = [FakeChat(101), FakeChat(202)]
+        client.get_participants.side_effect = [
+            [FakeMember(2), FakeMember(1)],
+            [FakeMember(4), FakeMember(3)],
+        ]
+
+        with (
+            patch.object(crawl, 'Chat', FakeChat),
+            patch.object(crawl, 'Channel', FakeChat),
+            patch.object(crawl, 'StringSession', return_value='session'),
+            patch.object(crawl, 'new_run_time', return_value='20260724120000'),
+        ):
+            result = crawl.main(['101', '202'])
+
+        self.assertEqual(result, 0)
+        self.assertEqual(client.get_entity.call_args_list, [call(101), call(202)])
+        self.assertNotIn(call(999), client.get_entity.call_args_list)
+        save_session.assert_called_once_with('updated-session')
+        self.assertEqual(save_group_export.call_count, 2)
+        first_members = save_group_export.call_args_list[0].args[2]
+        self.assertEqual([member.id for member in first_members], [1, 2])
+
+
+if __name__ == '__main__':
+    unittest.main()