diff --git a/swh/journal/serializers.py b/swh/journal/serializers.py
--- a/swh/journal/serializers.py
+++ b/swh/journal/serializers.py
@@ -66,6 +66,28 @@
         raise ValueError("Unknown object type: %s." % object_type)
 
 
+def stringify_key_item(k: str, v: Union[str, bytes]) -> str:
+    """Turn the item of a dict key into a string"""
+    if isinstance(v, str):
+        return v
+    if k == "url":
+        return v.decode("utf-8")
+    return v.hex()
+
+
+def pprint_key(key: KeyType) -> str:
+    """Pretty-print a kafka key"""
+
+    if isinstance(key, dict):
+        return "{%s}" % ", ".join(
+            f"{k}: {stringify_key_item(k, v)}" for k, v in key.items()
+        )
+    elif isinstance(key, bytes):
+        return key.hex()
+    else:
+        return key
+
+
 def key_to_kafka(key: KeyType) -> bytes:
     """Serialize a key, possibly a dict, in a predictable way"""
     p = msgpack.Packer(use_bin_type=True)
diff --git a/swh/journal/tests/test_serializers.py b/swh/journal/tests/test_serializers.py
--- a/swh/journal/tests/test_serializers.py
+++ b/swh/journal/tests/test_serializers.py
@@ -34,3 +34,20 @@
     for object_type, objects in TEST_OBJECTS.items():
         for obj in objects:
             assert serializers.object_key(object_type, obj) is not None
+
+
+def test_pprint_key():
+    """Test whether get_key works on all our objects"""
+    for object_type, objects in TEST_OBJECTS.items():
+        for obj in objects:
+            key = serializers.object_key(object_type, obj)
+            pprinted_key = serializers.pprint_key(key)
+            assert isinstance(pprinted_key, str)
+
+            if isinstance(key, dict):
+                assert pprinted_key[0], pprinted_key[-1] == "{}"
+                for dict_key in key.keys():
+                    assert f"{dict_key}:" in pprinted_key
+
+            if isinstance(key, bytes):
+                assert pprinted_key == key.hex()