diff --git a/swh/deposit/cli/client.py b/swh/deposit/cli/client.py
--- a/swh/deposit/cli/client.py
+++ b/swh/deposit/cli/client.py
@@ -60,7 +60,7 @@
 
 
 def generate_metadata(
-    deposit_client: str, name: str, external_id: str, authors: List[str]
+    deposit_client: str, name: str, external_id: Optional[str], authors: List[str]
 ) -> str:
     """Generate sword compliant xml metadata with the minimum required metadata.
 
@@ -94,11 +94,10 @@
     import xmltodict
 
     # generate a metadata file with the minimum required metadata
-    codemetadata = {
+    document = {
         "atom:entry": {
             "@xmlns:atom": "http://www.w3.org/2005/Atom",
             "@xmlns:codemeta": "https://doi.org/10.5063/SCHEMA/CODEMETA-2.0",
-            "codemeta:identifier": external_id,
             "atom:updated": datetime.now(tz=timezone.utc),  # mandatory, cf. docstring
             "atom:author": deposit_client,  # mandatory, cf. docstring
             "atom:title": name,  # mandatory, cf. docstring
@@ -108,8 +107,11 @@
             ],
         },
     }
-    logging.debug("Metadata dict to generate as xml: %s", codemetadata)
-    return xmltodict.unparse(codemetadata, pretty=True)
+    if external_id:
+        document["atom:entry"]["codemeta:identifier"] = external_id
+
+    logging.debug("Atom entry dict to generate as xml: %s", document)
+    return xmltodict.unparse(document, pretty=True)
 
 
 def _collection(client: PublicApiDepositClient) -> str:
@@ -183,10 +185,6 @@
             "swhid": optional deposit swhid
             "replace": whether the given deposit is to be replaced or not
     """
-
-    if not slug:  # generate one as this is mandatory
-        slug = generate_slug()
-
     if not metadata:
         if name and authors:
             metadata_path = os.path.join(temp_dir, "metadata.xml")
diff --git a/swh/deposit/client.py b/swh/deposit/client.py
--- a/swh/deposit/client.py
+++ b/swh/deposit/client.py
@@ -474,13 +474,15 @@
     """Post an archive (binary) deposit client."""
 
     def compute_headers(self, info):
-        return {
-            "SLUG": info["slug"],
+        headers = {
             "CONTENT_MD5": info["md5sum"],
             "IN-PROGRESS": str(info["in_progress"]),
             "CONTENT-TYPE": info["content-type"],
             "CONTENT-DISPOSITION": "attachment; filename=%s" % (info["filename"],),
         }
+        if "slug" in info:
+            headers["SLUG"] = info["slug"]
+        return headers
 
     def compute_information(self, *args, **kwargs) -> Dict[str, Any]:
         info = compute_unified_information(
@@ -504,11 +506,13 @@
     """Post a metadata deposit client."""
 
     def compute_headers(self, info):
-        return {
-            "SLUG": info["slug"],
+        headers = {
             "IN-PROGRESS": str(info["in_progress"]),
             "CONTENT-TYPE": "application/atom+xml;type=entry",
         }
+        if "slug" in info:
+            headers["SLUG"] = info["slug"]
+        return headers
 
     def compute_information(self, *args, **kwargs) -> Dict[str, Any]:
         info = compute_unified_information(
@@ -561,10 +565,11 @@
         ]
 
         headers = {
-            "SLUG": info["slug"],
             "CONTENT_MD5": info["md5sum"],
             "IN-PROGRESS": str(info["in_progress"]),
         }
+        if "slug" in info:
+            headers["SLUG"] = info["slug"]
 
         return files, headers
 
@@ -606,7 +611,7 @@
     def deposit_create(
         self,
         collection: str,
-        slug: str,
+        slug: Optional[str],
         archive: Optional[str] = None,
         metadata: Optional[str] = None,
         in_progress: bool = False,
@@ -635,7 +640,7 @@
         self,
         collection: str,
         deposit_id: int,
-        slug: str,
+        slug: Optional[str],
         archive: Optional[str] = None,
         metadata: Optional[str] = None,
         in_progress: bool = False,
diff --git a/swh/deposit/tests/cli/test_client.py b/swh/deposit/tests/cli/test_client.py
--- a/swh/deposit/tests/cli/test_client.py
+++ b/swh/deposit/tests/cli/test_client.py
@@ -379,9 +379,9 @@
 def test_cli_single_deposit_slug_generation(
     sample_archive, patched_tmp_path, requests_mock_datadir, cli_runner
 ):
-    """Single deposit scenario without providing the slug, the slug is generated nonetheless
-    https://docs.softwareheritage.org/devel/swh-deposit/getting-started.html#single-deposit
-    """  # noqa
+    """Single deposit scenario without providing the slug, it should
+    not be generated.
+    """
     metadata_path = os.path.join(patched_tmp_path, "metadata.xml")
     # fmt: off
     result = cli_runner.invoke(
@@ -409,7 +409,7 @@
     with open(metadata_path) as fd:
         metadata_xml = fd.read()
         actual_metadata = dict(parse_xml(metadata_xml))
-        assert actual_metadata["codemeta:identifier"] is not None
+        assert "codemeta:identifier" not in actual_metadata
 
 
 def test_cli_multisteps_deposit(