diff --git a/matcher/__init__.py b/matcher/__init__.py
new file mode 100644
index 0000000..5e9706c
--- /dev/null
+++ b/matcher/__init__.py
@@ -0,0 +1,13 @@
+"""Match OSM and Wikidata items."""
+
+
+CallParams = dict[str, str | int]
+
+user_agent = (
+    "osm-wikidata/0.1 (https://github.com/EdwardBetts/osm-wikidata; edward@4angle.com)"
+)
+
+
+def user_agent_headers() -> dict[str, str]:
+    """User-Agent headers."""
+    return {"User-Agent": user_agent}