diff --git a/swh/deposit/api/common.py b/swh/deposit/api/common.py
--- a/swh/deposit/api/common.py
+++ b/swh/deposit/api/common.py
@@ -4,16 +4,19 @@
 # See top-level LICENSE file for more information
 
 from abc import ABCMeta, abstractmethod
+import datetime
 import hashlib
-from typing import Sequence, Type
+import json
+from typing import Any, Dict, Optional, Sequence, Tuple, Type, Union
 
-from django.http import HttpResponse
+from django.http import FileResponse, HttpResponse
 from django.shortcuts import render
 from django.urls import reverse
 from django.utils import timezone
 from rest_framework import status
 from rest_framework.authentication import BaseAuthentication, BasicAuthentication
 from rest_framework.permissions import BasePermission, IsAuthenticated
+from rest_framework.request import Request
 from rest_framework.views import APIView
 
 from swh.model import hashutil
@@ -71,7 +74,7 @@
 
     """
 
-    def _read_headers(self, request):
+    def _read_headers(self, request: Request) -> Dict[str, Any]:
         """Read and unify the necessary headers from the request (those are
            not stored in the same location or not properly formatted).
 
@@ -123,7 +126,7 @@
             "metadata-relevant": metadata_relevant,
         }
 
-    def _compute_md5(self, filehandler):
+    def _compute_md5(self, filehandler) -> bytes:
         """Compute uploaded file's md5 sum.
 
         Args:
@@ -140,31 +143,36 @@
         return h.digest()
 
     def _deposit_put(
-        self, request, deposit_id=None, in_progress=False, external_id=None
-    ):
+        self,
+        request: Request,
+        deposit_id: Optional[int] = None,
+        in_progress: bool = False,
+        external_id: Optional[str] = None,
+    ) -> Deposit:
         """Save/Update a deposit in db.
 
         Args:
-            deposit_id (int): deposit identifier
-            in_progress (dict): The deposit's status
-            external_id (str): The external identifier to associate to
-              the deposit
+            request: request data
+            deposit_id: deposit identifier
+            in_progress: deposit status
+            external_id: external identifier to associate to the deposit
 
         Returns:
             The Deposit instance saved or updated.
 
         """
+        complete_date: Optional[datetime.datetime] = None
+        deposit_parent: Optional[Deposit] = None
+
         if in_progress is False:
             complete_date = timezone.now()
             status_type = DEPOSIT_STATUS_DEPOSITED
         else:
-            complete_date = None
             status_type = DEPOSIT_STATUS_PARTIAL
 
         if not deposit_id:
             try:
-                # find a deposit parent (same external id, status load
-                # to success)
+                # find a deposit parent (same external id, status load to success)
                 deposit_parent = (
                     Deposit.objects.filter(
                         external_id=external_id, status=DEPOSIT_STATUS_LOAD_SUCCESS
@@ -173,8 +181,10 @@
                     .get()
                 )  # noqa
             except Deposit.DoesNotExist:
-                deposit_parent = None
+                # then no parent for that deposit, deposit_parent already None
+                pass
 
+            assert external_id is not None
             deposit = Deposit(
                 collection=self._collection,
                 external_id=external_id,
@@ -208,20 +218,20 @@
 
     def _deposit_request_put(
         self,
-        deposit,
-        deposit_request_data,
-        replace_metadata=False,
-        replace_archives=False,
-    ):
+        deposit: Deposit,
+        deposit_request_data: Dict[str, Any],
+        replace_metadata: bool = False,
+        replace_archives: bool = False,
+    ) -> None:
         """Save a deposit request with metadata attached to a deposit.
 
         Args:
-            deposit (Deposit): The deposit concerned by the request
-            deposit_request_data (dict): The dictionary with at most 2 deposit
-            request types (archive, metadata) to associate to the deposit
-            replace_metadata (bool): Flag defining if we add or update
+            deposit: The deposit concerned by the request
+            deposit_request_data: The dictionary with at most 2 deposit
+              request types (archive, metadata) to associate to the deposit
+            replace_metadata: Flag defining if we add or update
               existing metadata to the deposit
-            replace_archives (bool): Flag defining if we add or update
+            replace_archives: Flag defining if we add or update
               archives to existing deposit
 
         Returns:
@@ -245,7 +255,7 @@
 
         metadata = deposit_request_data.get(METADATA_KEY)
         if metadata:
-            raw_metadata = deposit_request_data.get(RAW_METADATA_KEY)
+            raw_metadata = deposit_request_data[RAW_METADATA_KEY]
             deposit_request = DepositRequest(
                 type=METADATA_TYPE,
                 deposit=deposit,
@@ -256,8 +266,8 @@
 
         assert deposit_request is not None
 
-    def _delete_archives(self, collection_name, deposit_id):
-        """Delete archives reference from the deposit id.
+    def _delete_archives(self, collection_name: str, deposit_id: int) -> Dict:
+        """Delete archive references from the deposit id.
 
         """
         try:
@@ -270,12 +280,12 @@
 
         return {}
 
-    def _delete_deposit(self, collection_name, deposit_id):
+    def _delete_deposit(self, collection_name: str, deposit_id: int) -> Dict:
         """Delete deposit reference.
 
         Args:
-            collection_name (str): Client's name
-            deposit_id (id): The deposit to delete
+            collection_name: Client's collection
+            deposit_id: The deposit to delete
 
         Returns
             Empty dict when ok.
@@ -304,14 +314,16 @@
 
         return {}
 
-    def _check_preconditions_on(self, filehandler, md5sum, content_length=None):
+    def _check_preconditions_on(
+        self, filehandler, md5sum: str, content_length: Optional[int] = None
+    ) -> Optional[Dict]:
         """Check preconditions on provided file are respected. That is the
            length and/or the md5sum hash match the file's content.
 
         Args:
             filehandler (InMemoryUploadedFile): The file to check
-            md5sum (hex str): md5 hash expected from the file's content
-            content_length (int): the expected length if provided.
+            md5sum: md5 hash expected from the file's content
+            content_length: the expected length if provided.
 
         Returns:
             Either none if no error or a dictionary with a key error
@@ -347,13 +359,13 @@
 
     def _binary_upload(
         self,
-        request,
-        headers,
-        collection_name,
-        deposit_id=None,
-        replace_metadata=False,
-        replace_archives=False,
-    ):
+        request: Request,
+        headers: Dict[str, Any],
+        collection_name: str,
+        deposit_id: Optional[int] = None,
+        replace_metadata: bool = False,
+        replace_archives: bool = False,
+    ) -> Dict[str, Any]:
         """Binary upload routine.
 
         Other than such a request, a 415 response is returned.
@@ -447,7 +459,7 @@
             "archive": filehandler.name,
         }
 
-    def _read_metadata(self, metadata_stream):
+    def _read_metadata(self, metadata_stream) -> Tuple[bytes, Dict[str, Any]]:
         """Given a metadata stream, reads the metadata and returns both the
            parsed and the raw metadata.
 
@@ -458,13 +470,13 @@
 
     def _multipart_upload(
         self,
-        request,
-        headers,
-        collection_name,
-        deposit_id=None,
-        replace_metadata=False,
-        replace_archives=False,
-    ):
+        request: Request,
+        headers: Dict[str, Any],
+        collection_name: str,
+        deposit_id: Optional[int] = None,
+        replace_metadata: bool = False,
+        replace_archives: bool = False,
+    ) -> Dict:
         """Multipart upload supported with exactly:
         - 1 archive (zip)
         - 1 atom entry
@@ -474,13 +486,13 @@
         Args:
             request (Request): the request holding information to parse
                 and inject in db
-            headers (dict): request headers formatted
-            collection_name (str): the associated client
-            deposit_id (id): deposit identifier if provided
-            replace_metadata (bool): 'Update or add' request to existing
+            headers: request headers formatted
+            collection_name: the associated client
+            deposit_id: deposit identifier if provided
+            replace_metadata: 'Update or add' request to existing
               deposit. If False (default), this adds new metadata request to
               existing ones. Otherwise, this will replace existing metadata.
-            replace_archives (bool): 'Update or add' request to existing
+            replace_archives: 'Update or add' request to existing
               deposit. If False (default), this adds new archive request to
               existing ones. Otherwise, this will replace existing archives.
               ones.
@@ -507,14 +519,15 @@
 
         content_types_present = set()
 
-        data = {
+        data: Dict[str, Optional[Any]] = {
             "application/zip": None,  # expected either zip
             "application/x-tar": None,  # or x-tar
             "application/atom+xml": None,
         }
         for key, value in request.FILES.items():
             fh = value
-            if fh.content_type in content_types_present:
+            content_type = fh.content_type
+            if content_type in content_types_present:
                 return make_error_dict(
                     ERROR_CONTENT,
                     "Only 1 application/zip (or application/x-tar) archive "
@@ -525,8 +538,9 @@
                     "header in the multipart deposit",
                 )
 
-            content_types_present.add(fh.content_type)
-            data[fh.content_type] = fh
+            content_types_present.add(content_type)
+            assert content_type is not None
+            data[content_type] = fh
 
         if len(content_types_present) != 2:
             return make_error_dict(
@@ -576,6 +590,7 @@
             deposit, deposit_request_data, replace_metadata, replace_archives
         )
 
+        assert filehandler is not None
         return {
             "deposit_id": deposit.id,
             "deposit_date": deposit.reception_date,
@@ -585,25 +600,25 @@
 
     def _atom_entry(
         self,
-        request,
-        headers,
-        collection_name,
-        deposit_id=None,
-        replace_metadata=False,
-        replace_archives=False,
-    ):
+        request: Request,
+        headers: Dict[str, Any],
+        collection_name: str,
+        deposit_id: Optional[int] = None,
+        replace_metadata: bool = False,
+        replace_archives: bool = False,
+    ) -> Dict[str, Any]:
         """Atom entry deposit.
 
         Args:
             request (Request): the request holding information to parse
                 and inject in db
-            headers (dict): request headers formatted
-            collection_name (str): the associated client
-            deposit_id (id): deposit identifier if provided
-            replace_metadata (bool): 'Update or add' request to existing
+            headers: request headers formatted
+            collection_name: the associated client
+            deposit_id: deposit identifier if provided
+            replace_metadata: 'Update or add' request to existing
               deposit. If False (default), this adds new metadata request to
               existing ones. Otherwise, this will replace existing metadata.
-            replace_archives (bool): 'Update or add' request to existing
+            replace_archives: 'Update or add' request to existing
               deposit. If False (default), this adds new archive request to
               existing ones. Otherwise, this will replace existing archives.
               ones.
@@ -644,6 +659,10 @@
 
         external_id = metadata.get("external_identifier", headers["slug"])
 
+        # TODO: Determine if we are in the metadata-only deposit case. If it is, then
+        # save deposit and deposit request typed 'metadata' and send metadata to the
+        # metadata storage. Otherwise, do as existing deposit.
+
         deposit = self._deposit_put(
             request,
             deposit_id=deposit_id,
@@ -665,15 +684,17 @@
             "status": deposit.status,
         }
 
-    def _empty_post(self, request, headers, collection_name, deposit_id):
+    def _empty_post(
+        self, request: Request, headers: Dict, collection_name: str, deposit_id: int
+    ) -> Dict[str, Any]:
         """Empty post to finalize an empty deposit.
 
         Args:
-            request (Request): the request holding information to parse
+            request: the request holding information to parse
                 and inject in db
-            headers (dict): request headers formatted
-            collection_name (str): the associated client
-            deposit_id (id): deposit identifier
+            headers: request headers formatted
+            collection_name: the associated client
+            deposit_id: deposit identifier
 
         Returns:
             Dictionary of result with the deposit's id, the date
@@ -692,7 +713,9 @@
             "archive": None,
         }
 
-    def _make_iris(self, request, collection_name, deposit_id):
+    def _make_iris(
+        self, request: Request, collection_name: str, deposit_id: int
+    ) -> Dict[str, Any]:
         """Define the IRI endpoints
 
         Args:
@@ -710,7 +733,13 @@
             for iri in [EM_IRI, EDIT_SE_IRI, CONT_FILE_IRI, STATE_IRI]
         }
 
-    def additional_checks(self, request, headers, collection_name, deposit_id=None):
+    def additional_checks(
+        self,
+        request: Request,
+        headers: Dict[str, Any],
+        collection_name: str,
+        deposit_id: Optional[int] = None,
+    ) -> Dict[str, Any]:
         """Permit the child class to enrich additional checks.
 
         Returns:
@@ -719,22 +748,30 @@
         """
         return {}
 
-    def checks(self, request, collection_name, deposit_id=None):
+    def checks(
+        self, request: Request, collection_name: str, deposit_id: Optional[int] = None
+    ) -> Dict[str, Any]:
         try:
             self._collection = DepositCollection.objects.get(name=collection_name)
         except DepositCollection.DoesNotExist:
             return make_error_dict(
                 NOT_FOUND, f"Unknown collection name {collection_name}"
             )
+        assert self._collection is not None
 
         username = request.user.username
         if username:  # unauthenticated request can have the username empty
             try:
-                self._client = DepositClient.objects.get(username=username)
+                self._client: DepositClient = DepositClient.objects.get(  # type: ignore
+                    username=username
+                )
             except DepositClient.DoesNotExist:
                 return make_error_dict(NOT_FOUND, f"Unknown client name {username}")
 
-            if self._collection.id not in self._client.collections:
+            collection_id = self._collection.id
+            collections = self._client.collections
+            assert collections is not None
+            if collection_id not in collections:
                 return make_error_dict(
                     FORBIDDEN,
                     f"Client {username} cannot access collection {collection_name}",
@@ -762,7 +799,9 @@
 
         return {"headers": headers}
 
-    def restrict_access(self, request, deposit=None):
+    def restrict_access(
+        self, request: Request, deposit: Optional[Deposit] = None
+    ) -> Dict[str, Any]:
         if deposit:
             if request.method != "GET" and deposit.status != DEPOSIT_STATUS_PARTIAL:
                 summary = "You can only act on deposit with status '%s'" % (
@@ -772,24 +811,33 @@
                 return make_error_dict(
                     BAD_REQUEST, summary=summary, verbose_description=description
                 )
+        return {}
 
-    def _basic_not_allowed_method(self, request, method):
+    def _basic_not_allowed_method(self, request: Request, method: str):
         return make_error_response(
             request,
             METHOD_NOT_ALLOWED,
             f"{method} method is not supported on this endpoint",
         )
 
-    def get(self, request, *args, **kwargs):
+    def get(
+        self, request: Request, collection_name: str, deposit_id: int
+    ) -> Union[HttpResponse, FileResponse]:
         return self._basic_not_allowed_method(request, "GET")
 
-    def post(self, request, *args, **kwargs):
+    def post(
+        self, request: Request, collection_name: str, deposit_id: Optional[int] = None
+    ) -> HttpResponse:
         return self._basic_not_allowed_method(request, "POST")
 
-    def put(self, request, *args, **kwargs):
+    def put(
+        self, request: Request, collection_name: str, deposit_id: int
+    ) -> HttpResponse:
         return self._basic_not_allowed_method(request, "PUT")
 
-    def delete(self, request, *args, **kwargs):
+    def delete(
+        self, request: Request, collection_name: str, deposit_id: Optional[int] = None
+    ) -> HttpResponse:
         return self._basic_not_allowed_method(request, "DELETE")
 
 
@@ -798,7 +846,9 @@
 
     """
 
-    def get(self, request, collection_name, deposit_id, format=None):
+    def get(
+        self, request: Request, collection_name: str, deposit_id: int
+    ) -> Union[HttpResponse, FileResponse]:
         """Endpoint to create/add resources to deposit.
 
         Returns:
@@ -813,14 +863,22 @@
 
         r = self.process_get(request, collection_name, deposit_id)
 
-        if isinstance(r, tuple):
-            status, content, content_type = r
-            return HttpResponse(content, status=status, content_type=content_type)
-
-        return r
+        status, content, content_type = r
+        if content_type == "swh/generator":
+            with content as path:
+                return FileResponse(
+                    open(path, "rb"), status=status, content_type="application/zip"
+                )
+        if content_type == "application/json":
+            return HttpResponse(
+                json.dumps(content), status=status, content_type=content_type
+            )
+        return HttpResponse(content, status=status, content_type=content_type)
 
     @abstractmethod
-    def process_get(self, request, collection_name, deposit_id):
+    def process_get(
+        self, request: Request, collection_name: str, deposit_id: int
+    ) -> Tuple[int, Any, str]:
         """Routine to deal with the deposit's get processing.
 
         Returns:
@@ -835,7 +893,9 @@
 
     """
 
-    def post(self, request, collection_name, deposit_id=None, format=None):
+    def post(
+        self, request: Request, collection_name: str, deposit_id: Optional[int] = None
+    ) -> HttpResponse:
         """Endpoint to create/add resources to deposit.
 
         Returns:
@@ -867,11 +927,17 @@
             content_type="application/xml",
             status=_status,
         )
-        response._headers["location"] = "Location", data[_iri_key]
+        response._headers["location"] = "Location", data[_iri_key]  # type: ignore
         return response
 
     @abstractmethod
-    def process_post(self, request, headers, collection_name, deposit_id=None):
+    def process_post(
+        self,
+        request,
+        headers: Dict,
+        collection_name: str,
+        deposit_id: Optional[int] = None,
+    ) -> Tuple[int, str, Dict]:
         """Routine to deal with the deposit's processing.
 
         Returns
@@ -889,7 +955,9 @@
 
     """
 
-    def put(self, request, collection_name, deposit_id, format=None):
+    def put(
+        self, request: Request, collection_name: str, deposit_id: int
+    ) -> HttpResponse:
         """Endpoint to update deposit resources.
 
         Returns:
@@ -912,7 +980,9 @@
         return HttpResponse(status=status.HTTP_204_NO_CONTENT)
 
     @abstractmethod
-    def process_put(self, request, headers, collection_name, deposit_id):
+    def process_put(
+        self, request: Request, headers: Dict, collection_name: str, deposit_id: int
+    ) -> Dict[str, Any]:
         """Routine to deal with updating a deposit in some way.
 
         Returns
@@ -927,7 +997,9 @@
 
     """
 
-    def delete(self, request, collection_name, deposit_id):
+    def delete(
+        self, request: Request, collection_name: str, deposit_id: Optional[int] = None
+    ) -> HttpResponse:
         """Endpoint to delete some deposit's resources (archives, deposit).
 
         Returns:
@@ -940,6 +1012,7 @@
         if "error" in checks:
             return make_error_response_from_dict(request, checks["error"])
 
+        assert deposit_id is not None
         data = self.process_delete(request, collection_name, deposit_id)
         error = data.get("error")
         if error:
@@ -948,11 +1021,13 @@
         return HttpResponse(status=status.HTTP_204_NO_CONTENT)
 
     @abstractmethod
-    def process_delete(self, request, collection_name, deposit_id):
+    def process_delete(
+        self, request: Request, collection_name: str, deposit_id: int
+    ) -> Dict:
         """Routine to delete a resource.
 
         This is mostly not allowed except for the
         EM_IRI (cf. .api.deposit_update.APIUpdateArchive)
 
         """
-        pass
+        return {}
diff --git a/swh/deposit/api/deposit.py b/swh/deposit/api/deposit.py
--- a/swh/deposit/api/deposit.py
+++ b/swh/deposit/api/deposit.py
@@ -3,6 +3,8 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+from typing import Any, Dict, Optional, Tuple
+
 from rest_framework import status
 
 from ..config import EDIT_SE_IRI
@@ -32,7 +34,13 @@
         SWHAtomEntryParser,
     )
 
-    def additional_checks(self, req, headers, collection_name, deposit_id=None):
+    def additional_checks(
+        self,
+        req,
+        headers: Dict[str, Any],
+        collection_name: str,
+        deposit_id: Optional[int] = None,
+    ) -> Dict[str, Any]:
         slug = headers["slug"]
         if not slug:
             msg = "Missing SLUG header in request"
@@ -41,7 +49,13 @@
 
         return {}
 
-    def process_post(self, req, headers, collection_name, deposit_id=None):
+    def process_post(
+        self,
+        req,
+        headers: Dict[str, Any],
+        collection_name: str,
+        deposit_id: Optional[int] = None,
+    ) -> Tuple[int, str, Dict[str, Any]]:
         """Create a first deposit as:
         - archive deposit (1 zip)
         - multipart (1 zip + 1 atom entry)
diff --git a/swh/deposit/api/deposit_content.py b/swh/deposit/api/deposit_content.py
--- a/swh/deposit/api/deposit_content.py
+++ b/swh/deposit/api/deposit_content.py
@@ -3,6 +3,7 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+from django.http import HttpResponse
 from django.shortcuts import render
 from rest_framework import status
 
@@ -12,7 +13,7 @@
 
 
 class APIContent(APIBase):
-    def get(self, req, collection_name, deposit_id, format=None):
+    def get(self, req, collection_name: str, deposit_id: int) -> HttpResponse:
         checks = self.checks(req, collection_name, deposit_id)
         if "error" in checks:
             return make_error_response_from_dict(req, checks["error"])
diff --git a/swh/deposit/api/deposit_status.py b/swh/deposit/api/deposit_status.py
--- a/swh/deposit/api/deposit_status.py
+++ b/swh/deposit/api/deposit_status.py
@@ -3,6 +3,7 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+from django.http import HttpResponse
 from django.shortcuts import render
 from rest_framework import status
 
@@ -21,7 +22,7 @@
 
     """
 
-    def get(self, req, collection_name, deposit_id, format=None):
+    def get(self, req, collection_name: str, deposit_id: int) -> HttpResponse:
         checks = self.checks(req, collection_name, deposit_id)
         if "error" in checks:
             return make_error_response_from_dict(req, checks["error"])
diff --git a/swh/deposit/api/deposit_update.py b/swh/deposit/api/deposit_update.py
--- a/swh/deposit/api/deposit_update.py
+++ b/swh/deposit/api/deposit_update.py
@@ -3,6 +3,8 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+from typing import Any, Dict, Optional, Tuple
+
 from rest_framework import status
 
 from ..config import CONT_FILE_IRI, EDIT_SE_IRI, EM_IRI
@@ -30,7 +32,9 @@
         SWHFileUploadTarParser,
     )
 
-    def process_put(self, req, headers, collection_name, deposit_id):
+    def process_put(
+        self, req, headers, collection_name: str, deposit_id: int
+    ) -> Dict[str, Any]:
         """Replace existing content for the existing deposit.
 
            source: http://swordapp.github.io/SWORDv2-Profile/SWORDProfile.html#protocoloperations_editingcontent_binary  # noqa
@@ -49,7 +53,9 @@
             req, headers, collection_name, deposit_id=deposit_id, replace_archives=True
         )
 
-    def process_post(self, req, headers, collection_name, deposit_id):
+    def process_post(
+        self, req, headers: Dict, collection_name: str, deposit_id: Optional[int] = None
+    ) -> Tuple[int, str, Dict]:
         """Add new content to the existing deposit.
 
            source: http://swordapp.github.io/SWORDv2-Profile/SWORDProfile.html#protocoloperations_addingcontent_mediaresource  # noqa
@@ -65,7 +71,8 @@
             msg = "Packaging format supported is restricted to %s" % (
                 ", ".join(ACCEPT_ARCHIVE_CONTENT_TYPES)
             )
-            return "unused", "unused", make_error_dict(BAD_REQUEST, msg)
+            unused = 0
+            return unused, "unused", make_error_dict(BAD_REQUEST, msg)
 
         return (
             status.HTTP_201_CREATED,
@@ -73,7 +80,7 @@
             self._binary_upload(req, headers, collection_name, deposit_id),
         )
 
-    def process_delete(self, req, collection_name, deposit_id):
+    def process_delete(self, req, collection_name: str, deposit_id: int) -> Dict:
         """Delete content (archives) from existing deposit.
 
            source: http://swordapp.github.io/SWORDv2-Profile/SWORDProfile.html#protocoloperations_deletingcontent  # noqa
@@ -96,7 +103,9 @@
 
     parser_classes = (SWHMultiPartParser, SWHAtomEntryParser)
 
-    def process_put(self, req, headers, collection_name, deposit_id):
+    def process_put(
+        self, req, headers: Dict, collection_name: str, deposit_id: int
+    ) -> Dict[str, Any]:
         """Replace existing deposit's metadata/archive with new ones.
 
            source:
@@ -120,7 +129,13 @@
             req, headers, collection_name, deposit_id=deposit_id, replace_metadata=True
         )
 
-    def process_post(self, req, headers, collection_name, deposit_id):
+    def process_post(
+        self,
+        request,
+        headers: Dict,
+        collection_name: str,
+        deposit_id: Optional[int] = None,
+    ) -> Tuple[int, str, Dict]:
         """Add new metadata/archive to existing deposit.
 
            source:
@@ -139,28 +154,29 @@
             For the empty post case, this returns a 200.
 
         """
-        if req.content_type.startswith("multipart/"):
+        assert deposit_id is not None
+        if request.content_type.startswith("multipart/"):
             return (
                 status.HTTP_201_CREATED,
                 EM_IRI,
                 self._multipart_upload(
-                    req, headers, collection_name, deposit_id=deposit_id
+                    request, headers, collection_name, deposit_id=deposit_id
                 ),
             )
         # check for final empty post
         # source: http://swordapp.github.io/SWORDv2-Profile/SWORDProfile.html
         # #continueddeposit_complete
         if headers["content-length"] == 0 and headers["in-progress"] is False:
-            data = self._empty_post(req, headers, collection_name, deposit_id)
+            data = self._empty_post(request, headers, collection_name, deposit_id)
             return (status.HTTP_200_OK, EDIT_SE_IRI, data)
 
         return (
             status.HTTP_201_CREATED,
             EM_IRI,
-            self._atom_entry(req, headers, collection_name, deposit_id=deposit_id),
+            self._atom_entry(request, headers, collection_name, deposit_id=deposit_id),
         )
 
-    def process_delete(self, req, collection_name, deposit_id):
+    def process_delete(self, req, collection_name: str, deposit_id: int) -> Dict:
         """Delete the container (deposit).
 
            source: http://swordapp.github.io/SWORDv2-Profile/SWORDProfile.html#protocoloperations_deleteconteiner  # noqa
diff --git a/swh/deposit/api/private/__init__.py b/swh/deposit/api/private/__init__.py
--- a/swh/deposit/api/private/__init__.py
+++ b/swh/deposit/api/private/__init__.py
@@ -86,23 +86,11 @@
         return {"headers": headers}
 
     def get(
-        self,
-        request,
-        collection_name=None,
-        deposit_id=None,
-        format=None,
-        *args,
-        **kwargs,
+        self, request, collection_name=None, deposit_id=None, *args, **kwargs,
     ):
-        return super().get(request, collection_name, deposit_id, format)
+        return super().get(request, collection_name, deposit_id)
 
     def put(
-        self,
-        request,
-        collection_name=None,
-        deposit_id=None,
-        format=None,
-        *args,
-        **kwargs,
+        self, request, collection_name=None, deposit_id=None, *args, **kwargs,
     ):
-        return super().put(request, collection_name, deposit_id, format)
+        return super().put(request, collection_name, deposit_id)
diff --git a/swh/deposit/api/private/deposit_check.py b/swh/deposit/api/private/deposit_check.py
--- a/swh/deposit/api/private/deposit_check.py
+++ b/swh/deposit/api/private/deposit_check.py
@@ -4,10 +4,10 @@
 # See top-level LICENSE file for more information
 
 from itertools import chain
-import json
 import re
 from shutil import get_unpack_formats
 import tarfile
+from typing import Dict, Optional, Tuple
 import zipfile
 
 from rest_framework import status
@@ -16,7 +16,7 @@
 
 from . import APIPrivateView, DepositReadMixin
 from ...config import ARCHIVE_TYPE, DEPOSIT_STATUS_REJECTED, DEPOSIT_STATUS_VERIFIED
-from ...models import Deposit
+from ...models import Deposit, DepositRequest
 from ..common import APIGet
 
 MANDATORY_FIELDS_MISSING = "Mandatory fields are missing"
@@ -60,7 +60,7 @@
 
     """
 
-    def _check_deposit_archives(self, deposit):
+    def _check_deposit_archives(self, deposit: Deposit) -> Tuple[bool, Optional[Dict]]:
         """Given a deposit, check each deposit request of type archive.
 
         Args:
@@ -87,7 +87,9 @@
             return True, None
         return False, {"archive": errors}
 
-    def _check_archive(self, archive_request):
+    def _check_archive(
+        self, archive_request: DepositRequest
+    ) -> Tuple[bool, Optional[str]]:
         """Check that a deposit associated archive is ok:
         - readable
         - supported archive format
@@ -111,11 +113,11 @@
 
         try:
             if zipfile.is_zipfile(archive_path):
-                with zipfile.ZipFile(archive_path) as f:
-                    files = f.namelist()
+                with zipfile.ZipFile(archive_path) as zipfile_:
+                    files = zipfile_.namelist()
             elif tarfile.is_tarfile(archive_path):
-                with tarfile.open(archive_path) as f:
-                    files = f.getnames()
+                with tarfile.open(archive_path) as tarfile_:
+                    files = tarfile_.getnames()
             else:
                 return False, MANDATORY_ARCHIVE_UNSUPPORTED
         except Exception:
@@ -128,7 +130,7 @@
             return False, MANDATORY_ARCHIVE_INVALID
         return True, None
 
-    def _check_metadata(self, metadata):
+    def _check_metadata(self, metadata: Dict) -> Tuple[bool, Optional[Dict]]:
         """Check to execute on all metadata for mandatory field presence.
 
         Args:
@@ -174,7 +176,9 @@
             )
         return False, {"metadata": detail}
 
-    def process_get(self, req, collection_name, deposit_id):
+    def process_get(
+        self, req, collection_name: str, deposit_id: int
+    ) -> Tuple[int, Dict, str]:
         """Build a unique tarball from the multiple received and stream that
            content to the client.
 
@@ -189,15 +193,17 @@
         """
         deposit = Deposit.objects.get(pk=deposit_id)
         metadata = self._metadata_get(deposit)
-        problems = {}
+        problems: Dict = {}
         # will check each deposit's associated request (both of type
         # archive and metadata) for errors
         archives_status, error_detail = self._check_deposit_archives(deposit)
         if not archives_status:
+            assert error_detail is not None
             problems.update(error_detail)
 
         metadata_status, error_detail = self._check_metadata(metadata)
         if not metadata_status:
+            assert error_detail is not None
             problems.update(error_detail)
 
         deposit_status = archives_status and metadata_status
@@ -225,4 +231,4 @@
 
         deposit.save()
 
-        return status.HTTP_200_OK, json.dumps(response), "application/json"
+        return status.HTTP_200_OK, response, "application/json"
diff --git a/swh/deposit/api/private/deposit_read.py b/swh/deposit/api/private/deposit_read.py
--- a/swh/deposit/api/private/deposit_read.py
+++ b/swh/deposit/api/private/deposit_read.py
@@ -4,12 +4,11 @@
 # See top-level LICENSE file for more information
 
 from contextlib import contextmanager
-import json
 import os
 import shutil
 import tempfile
+from typing import Any, Dict, Tuple
 
-from django.http import FileResponse
 from rest_framework import status
 
 from swh.core import tarball
@@ -74,14 +73,16 @@
         if not os.path.exists(self.extraction_dir):
             os.makedirs(self.extraction_dir)
 
-    def process_get(self, request, collection_name, deposit_id):
+    def process_get(
+        self, request, collection_name: str, deposit_id: int
+    ) -> Tuple[int, Any, str]:
         """Build a unique tarball from the multiple received and stream that
            content to the client.
 
         Args:
             request (Request):
-            collection_name (str): Collection owning the deposit
-            deposit_id (id): Deposit concerned by the reading
+            collection_name: Collection owning the deposit
+            deposit_id: Deposit concerned by the reading
 
         Returns:
             Tuple status, stream of content, content-type
@@ -91,12 +92,11 @@
             r.archive.path
             for r in self._deposit_requests(deposit_id, request_type=ARCHIVE_TYPE)
         ]
-        with aggregate_tarballs(self.extraction_dir, archive_paths) as path:
-            return FileResponse(
-                open(path, "rb"),
-                status=status.HTTP_200_OK,
-                content_type="application/zip",
-            )
+        return (
+            status.HTTP_200_OK,
+            aggregate_tarballs(self.extraction_dir, archive_paths),
+            "swh/generator",
+        )
 
 
 class APIReadMetadata(APIPrivateView, APIGet, DepositReadMixin):
@@ -187,11 +187,9 @@
 
         return data
 
-    def process_get(self, request, collection_name, deposit_id):
+    def process_get(
+        self, request, collection_name: str, deposit_id: int
+    ) -> Tuple[int, Dict, str]:
         deposit = Deposit.objects.get(pk=deposit_id)
         data = self.metadata_read(deposit)
-        d = {}
-        if data:
-            d = json.dumps(data)
-
-        return status.HTTP_200_OK, d, "application/json"
+        return status.HTTP_200_OK, data if data else {}, "application/json"
diff --git a/swh/deposit/api/private/deposit_update_status.py b/swh/deposit/api/private/deposit_update_status.py
--- a/swh/deposit/api/private/deposit_update_status.py
+++ b/swh/deposit/api/private/deposit_update_status.py
@@ -3,6 +3,8 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+from typing import Dict
+
 from rest_framework.parsers import JSONParser
 
 from swh.model.identifiers import DIRECTORY, REVISION, SNAPSHOT, swhid
@@ -61,7 +63,9 @@
 
         return {}
 
-    def process_put(self, request, headers, collection_name, deposit_id):
+    def process_put(
+        self, request, headers: Dict, collection_name: str, deposit_id: int
+    ) -> Dict:
         """Update the deposit with status and SWHIDs
 
         Returns: