diff --git a/swh/indexer/cli.py b/swh/indexer/cli.py
--- a/swh/indexer/cli.py
+++ b/swh/indexer/cli.py
@@ -215,7 +215,14 @@
 @indexer_cli_group.command("journal-client")
 @click.argument(
     "indexer",
-    type=click.Choice(["origin-intrinsic-metadata", "extrinsic-metadata", "*"]),
+    type=click.Choice(
+        [
+            "origin-intrinsic-metadata",
+            "extrinsic-metadata",
+            "content-mimetype",
+            "*",
+        ]
+    ),
     required=False
     # TODO: remove required=False after we stop using it
 )
@@ -321,6 +328,14 @@
         idx.catch_exceptions = False  # don't commit offsets if indexation failed
         worker_fns.append(idx.process_journal_objects)
 
+    if indexer in ("content-mimetype", "*"):
+        from swh.indexer.mimetype import MimetypeIndexer
+
+        object_types.add("content")
+        idx = MimetypeIndexer()
+        idx.catch_exceptions = False  # don't commit offsets if indexation failed
+        worker_fns.append(idx.process_journal_objects)
+
     if not worker_fns:
         raise click.ClickException(f"Unknown indexer: {indexer}")
 
diff --git a/swh/indexer/indexer.py b/swh/indexer/indexer.py
--- a/swh/indexer/indexer.py
+++ b/swh/indexer/indexer.py
@@ -41,6 +41,9 @@
 
 
 class ObjectsDict(TypedDict, total=False):
+    """Typed objects."""
+
+    content: List[Dict]
     directory: List[Dict]
     origin: List[Dict]
     origin_visit_status: List[Dict]
@@ -282,12 +285,23 @@
         """
         return {}
 
+    def process_journal_objects(self, objects: ObjectsDict) -> Dict:
+        """Read swh message objects (content, origin, ...) from the journal to:
+
+        - retrieve the associated objects from the storage backend (e.g. storage,
+          objstorage...)
+        - execute the associated indexing computations
+        - store the results in the indexer storage
+
+        """
+        raise NotImplementedError()
+
 
 class ContentIndexer(BaseIndexer[Sha1, bytes, TResult], Generic[TResult]):
-    """A content indexer working on a list of ids directly.
+    """A content indexer working on the journal (method `process_journal_objects`) or on
+    a list of ids directly (method `run`).
 
-    To work on indexer partition, use the :class:`ContentPartitionIndexer`
-    instead.
+    To work on indexer partition, use the :class:`ContentPartitionIndexer` instead.
 
     Note: :class:`ContentIndexer` is not an instantiable object. To
     use it, one should inherit from this class and override the
@@ -295,6 +309,44 @@
 
     """
 
+    def process_journal_objects(self, objects: ObjectsDict) -> Dict:
+        """Read content objects from the journal, retrieve their raw content and compute
+        content indexing (e.g. mimetype, fossology license, ...).
+
+        Note that once this is deployed, this supersedes the main ContentIndexer.run
+        method call and the class ContentPartitionIndexer.
+
+        """
+        summary: Dict[str, Any] = {"status": "uneventful"}
+        try:
+            results = []
+            contents = objects.get("content", [])
+            # FIXME: with swh.objstorage > v2.0: self.objstorage.get_batch(contents)
+            content_data = self.objstorage.get_batch(c["sha1"] for c in contents)
+            for item, raw_content in zip(contents, content_data):
+                id_ = item["sha1"]
+                if not raw_content:
+                    self.log.warning(
+                        "Content %s not found in objstorage", hashutil.hash_to_hex(id_)
+                    )
+                    continue
+
+                results.extend(self.index(id_, data=raw_content))
+        except Exception:
+            if not self.catch_exceptions:
+                raise
+            summary["status"] = "failed"
+            return summary
+
+        summary_persist = self.persist_index_computations(results)
+        self.results = results
+        if summary_persist:
+            for value in summary_persist.values():
+                if value > 0:
+                    summary["status"] = "eventful"
+            summary.update(summary_persist)
+        return summary
+
     def run(self, ids: List[Sha1], **kwargs) -> Dict:
         """Given a list of ids: