diff --git a/swh/loader/package/nixguix/loader.py b/swh/loader/package/nixguix/loader.py
--- a/swh/loader/package/nixguix/loader.py
+++ b/swh/loader/package/nixguix/loader.py
@@ -5,7 +5,6 @@
 
 import json
 import logging
-import requests
 from typing import Any, Dict, Iterator, Mapping, Optional, Tuple
 
 import attr
@@ -22,7 +21,7 @@
     Sha1Git,
 )
 
-from swh.loader.package.utils import EMPTY_AUTHOR
+from swh.loader.package.utils import EMPTY_AUTHOR, api_info
 from swh.loader.package.loader import (
     BasePackageInfo,
     PackageLoader,
@@ -207,11 +206,7 @@
 
 
 def retrieve_sources(url: str) -> bytes:
-    response = requests.get(url, allow_redirects=True)
-    if response.status_code != 200:
-        raise ValueError("Got %d HTTP code on %s", response.status_code, url)
-
-    return response.content
+    return api_info(url, allow_redirects=True)
 
 
 def parse_sources(raw_sources: bytes) -> Dict[str, Any]:
diff --git a/swh/loader/package/npm/loader.py b/swh/loader/package/npm/loader.py
--- a/swh/loader/package/npm/loader.py
+++ b/swh/loader/package/npm/loader.py
@@ -96,7 +96,7 @@
 
         """
         if not self._info:
-            self._info = api_info(self.provider_url)
+            self._info = json.loads(api_info(self.provider_url))
         return self._info
 
     def get_versions(self) -> Sequence[str]:
diff --git a/swh/loader/package/pypi/loader.py b/swh/loader/package/pypi/loader.py
--- a/swh/loader/package/pypi/loader.py
+++ b/swh/loader/package/pypi/loader.py
@@ -1,10 +1,11 @@
-# Copyright (C) 2019  The Software Heritage developers
+# Copyright (C) 2019-2020  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
-import os
 import logging
+import json
+import os
 from typing import Any, Dict, Iterator, Optional, Sequence, Tuple
 from urllib.parse import urlparse
 
@@ -63,7 +64,7 @@
 
         """
         if not self._info:
-            self._info = api_info(self.provider_url)
+            self._info = json.loads(api_info(self.provider_url))
         return self._info
 
     def get_versions(self) -> Sequence[str]:
diff --git a/swh/loader/package/tests/test_utils.py b/swh/loader/package/tests/test_utils.py
--- a/swh/loader/package/tests/test_utils.py
+++ b/swh/loader/package/tests/test_utils.py
@@ -1,12 +1,13 @@
-# Copyright (C) 2019  The Software Heritage developers
+# Copyright (C) 2019-2020  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 
+import json
 import os
-import pytest
 
+import pytest
 
 import swh.loader.package
 from swh.loader.package.utils import download, api_info, release_name
@@ -144,7 +145,7 @@
     """Fetching json info from pypi project should be ok"""
     url = "https://pypi.org/pypi/requests/json"
     requests_mock.get(url, text='{"version": "0.0.1"}')
-    actual_info = api_info(url)
+    actual_info = json.loads(api_info(url))
     assert actual_info == {
         "version": "0.0.1",
     }
diff --git a/swh/loader/package/utils.py b/swh/loader/package/utils.py
--- a/swh/loader/package/utils.py
+++ b/swh/loader/package/utils.py
@@ -25,7 +25,7 @@
 EMPTY_AUTHOR = Person(fullname=b"", name=None, email=None,)
 
 
-def api_info(url: str) -> Dict:
+def api_info(url: str, **extra_params) -> bytes:
     """Basic api client to retrieve information on project. This deals with
        fetching json metadata about pypi projects.
 
@@ -36,13 +36,13 @@
         ValueError in case of query failures (for some reasons: 404, ...)
 
     Returns:
-        The associated response's information dict
+        The associated response's information
 
     """
-    response = requests.get(url, **DEFAULT_PARAMS)
+    response = requests.get(url, **{**DEFAULT_PARAMS, **extra_params})
     if response.status_code != 200:
         raise ValueError("Fail to query '%s'. Reason: %s" % (url, response.status_code))
-    return response.json()
+    return response.content
 
 
 def download(