diff --git a/swh/lister/bitbucket/lister.py b/swh/lister/bitbucket/lister.py
--- a/swh/lister/bitbucket/lister.py
+++ b/swh/lister/bitbucket/lister.py
@@ -17,6 +17,7 @@
     PATH_TEMPLATE = '/repositories?after=%s'
     MODEL = BitBucketModel
     LISTER_NAME = 'bitbucket'
+    instance = 'bitbucket'
 
     def get_model_from_repo(self, repo):
         return {
diff --git a/swh/lister/core/lister_base.py b/swh/lister/core/lister_base.py
--- a/swh/lister/core/lister_base.py
+++ b/swh/lister/core/lister_base.py
@@ -239,12 +239,9 @@
     @property
     def ADDITIONAL_CONFIG(self):  # noqa: N802
         return {
-            'credentials':
-                ('list[dict]', []),
-            'cache_responses':
-                ('bool', False),
-            'cache_dir':
-                ('str', '~/.cache/swh/lister/%s' % self.LISTER_NAME),
+            'credentials': ('dict', {}),
+            'cache_responses': ('bool', False),
+            'cache_dir': ('str', '~/.cache/swh/lister/%s' % self.LISTER_NAME),
         }
 
     INITIAL_BACKOFF = 10
diff --git a/swh/lister/core/lister_transports.py b/swh/lister/core/lister_transports.py
--- a/swh/lister/core/lister_transports.py
+++ b/swh/lister/core/lister_transports.py
@@ -62,13 +62,19 @@
         """Get the full parameters passed to requests given the
         transport_request identifier.
 
+        This uses credentials if any are provided. The 'credentials'
+        configuration is expected to be a dict of multiple levels. The first
+        level is the lister's name, the second is the lister's instance name.
+
         MAY BE OVERRIDDEN if something more complex than the request headers
         is needed.
 
         """
         params = {}
         params['headers'] = self.request_headers() or {}
-        creds = self.config['credentials']
+        all_creds = self.config['credentials']
+        lister_creds = all_creds.get(self.LISTER_NAME, {})
+        creds = lister_creds.get(self.instance, {})
         auth = random.choice(creds) if creds else None
         if auth:
             params['auth'] = (auth['username'], auth['password'])
diff --git a/swh/lister/debian/lister.py b/swh/lister/debian/lister.py
--- a/swh/lister/debian/lister.py
+++ b/swh/lister/debian/lister.py
@@ -32,6 +32,7 @@
     MODEL = Package
     PATH_TEMPLATE = None
     LISTER_NAME = 'debian'
+    instance = 'debian'
 
     def __init__(self, override_config=None):
         SWHListerHttpTransport.__init__(self, api_baseurl="bogus")
diff --git a/swh/lister/github/lister.py b/swh/lister/github/lister.py
--- a/swh/lister/github/lister.py
+++ b/swh/lister/github/lister.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2017-2018 the Software Heritage developers
+# Copyright (C) 2017-2019 the Software Heritage developers
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
@@ -14,6 +14,7 @@
     MODEL = GitHubModel
     API_URL_INDEX_RE = re.compile(r'^.*/repositories\?since=(\d+)')
     LISTER_NAME = 'github'
+    instance = 'github'  # There is only 1 instance of such lister
 
     def get_model_from_repo(self, repo):
         return {
diff --git a/swh/lister/gitlab/lister.py b/swh/lister/gitlab/lister.py
--- a/swh/lister/gitlab/lister.py
+++ b/swh/lister/gitlab/lister.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2018 the Software Heritage developers
+# Copyright (C) 2018-2019 the Software Heritage developers
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
@@ -28,19 +28,6 @@
             self.PATH_TEMPLATE = '%s&per_page=%s' % (
                 self.PATH_TEMPLATE, per_page)
 
-    @property
-    def ADDITIONAL_CONFIG(self):
-        """Override additional config as the 'credentials' structure change
-           between the ancestor classes and this class.
-
-           cf. request_params method below
-
-        """
-        default_config = super().ADDITIONAL_CONFIG
-        # 'credentials' is a dict of (instance, {username, password}) dict
-        default_config['credentials'] = ('dict', {})
-        return default_config
-
     def request_params(self, identifier):
         """Get the full parameters passed to requests given the
         transport_request identifier.
diff --git a/swh/lister/npm/lister.py b/swh/lister/npm/lister.py
--- a/swh/lister/npm/lister.py
+++ b/swh/lister/npm/lister.py
@@ -14,6 +14,7 @@
     """
     MODEL = NpmModel
     LISTER_NAME = 'npm'
+    instance = 'npm'
 
     def __init__(self, api_baseurl='https://replicate.npmjs.com',
                  per_page=1000, override_config=None):
diff --git a/swh/lister/pypi/lister.py b/swh/lister/pypi/lister.py
--- a/swh/lister/pypi/lister.py
+++ b/swh/lister/pypi/lister.py
@@ -16,6 +16,7 @@
     MODEL = PyPIModel
     LISTER_NAME = 'pypi'
     PAGE = 'https://pypi.org/simple/'
+    instance = 'pypi'  # As of today only the main pypi.org is used
 
     def __init__(self, override_config=None):
         ListerOnePageApiTransport .__init__(self)