diff --git a/README.md b/README.md
index 62993b5..b4fb7d4 100644
--- a/README.md
+++ b/README.md
@@ -869,6 +869,26 @@ Add:
 There is no need to run `source`, activate the virtual environment, or use a
 wrapper script.
 
+## Sending an ntfy notification
+
+`ntfy_notify.py` provides both a command-line interface and a reusable Python
+function. Send a message from the command line with:
+
+```bash
+/opt/ups/.venv/bin/python /opt/ups/ntfy_notify.py "Some text"
+```
+
+Use it as a Python library with:
+
+```python
+from ntfy_notify import send_notification
+
+send_notification("Some text")
+```
+
+The default topic can be overridden with `--topic-url` or the
+`NTFY_TOPIC_URL` environment variable.
+
 After a few minutes:
 
 ```bash
diff --git a/ntfy_notify.py b/ntfy_notify.py
new file mode 100755
index 0000000..8c18172
--- /dev/null
+++ b/ntfy_notify.py
@@ -0,0 +1,95 @@
+#!/usr/bin/env python3
+
+"""Send a text notification to the Home Alert ntfy topic."""
+
+import argparse
+import os
+import sys
+from urllib.error import HTTPError, URLError
+from urllib.request import Request, urlopen
+
+
+DEFAULT_TOPIC_URL = (
+    "https://ntfy.sh/VK20_Home_Alert_______4671938674123049873459"
+)
+
+
+def send_notification(
+    message,
+    topic_url=None,
+    timeout=10,
+):
+    """Send *message* to ntfy and return the server response body."""
+
+    if not isinstance(message, str):
+        raise TypeError("message must be a string")
+
+    if not message:
+        raise ValueError("message must not be empty")
+
+    url = topic_url or os.environ.get(
+        "NTFY_TOPIC_URL",
+        DEFAULT_TOPIC_URL,
+    )
+    request = Request(
+        url,
+        data=message.encode("utf-8"),
+        headers={"Content-Type": "text/plain; charset=utf-8"},
+        method="POST",
+    )
+
+    with urlopen(request, timeout=timeout) as response:
+        return response.read().decode("utf-8")
+
+
+def parse_arguments():
+    """Parse command-line arguments."""
+
+    parser = argparse.ArgumentParser(
+        description="Send a text message to the Home Alert ntfy topic.",
+    )
+    parser.add_argument(
+        "message",
+        nargs="+",
+        help="notification text",
+    )
+    parser.add_argument(
+        "--topic-url",
+        help="override the ntfy topic URL",
+    )
+    parser.add_argument(
+        "--timeout",
+        type=float,
+        default=10,
+        help="request timeout in seconds (default: 10)",
+    )
+    return parser.parse_args()
+
+
+def main():
+    args = parse_arguments()
+
+    try:
+        response = send_notification(
+            " ".join(args.message),
+            topic_url=args.topic_url,
+            timeout=args.timeout,
+        )
+        print(response)
+        return 0
+
+    except HTTPError as exc:
+        print(
+            f"ntfy returned HTTP {exc.code}: {exc.reason}",
+            file=sys.stderr,
+        )
+    except URLError as exc:
+        print(f"Could not reach ntfy: {exc.reason}", file=sys.stderr)
+    except (TypeError, ValueError) as exc:
+        print(f"Invalid notification: {exc}", file=sys.stderr)
+
+    return 1
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())