diff --git a/conftest.py b/conftest.py
--- a/conftest.py
+++ b/conftest.py
@@ -1,6 +1,76 @@
+# Copyright (C) 2019 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 pytest
+
 from hypothesis import settings
+from typing import Dict
+
 
 # define tests profile. Full documentation is at:
 # https://hypothesis.readthedocs.io/en/latest/settings.html#settings-profiles
 settings.register_profile("fast", max_examples=5, deadline=5000)
 settings.register_profile("slow", max_examples=20, deadline=5000)
+
+
+@pytest.fixture
+def sample_data() -> Dict:
+    """Pre-defined sample storage object data to manipulate
+
+    Returns:
+        Dict of data (keys: content, directory, revision, person)
+
+    """
+    sample_content = {
+        'blake2s256': b'\xbf?\x05\xed\xc1U\xd2\xc5\x168Xm\x93\xde}f(HO@\xd0\xacn\x04\x1e\x9a\xb9\xfa\xbf\xcc\x08\xc7',  # noqa
+        'sha1': b'g\x15y+\xcb][\\\n\xf28\xb2\x0c_P[\xc8\x89Hk',
+        'sha1_git': b'\xf2\xae\xfa\xba\xfa\xa6B\x9b^\xf9Z\xf5\x14\x0cna\xb0\xef\x8b',  # noqa
+        'sha256': b"\x87\x022\xedZN\x84\xe8za\xf8'(oA\xc9k\xb1\x80c\x80\xe7J\x06\xea\xd2\xd5\xbeB\x19\xb8\xce",  # noqa
+        'length': 48,
+        'data': b'temp file for testing content storage conversion',
+        'status': 'visible',
+    }
+
+    sample_content2 = {
+        'blake2s256': b'\xbf?\x05\xed\xc1U\xd2\xc5\x168Xm\x93\xde}f(HO@\xd0\xacn\x04\x1e\x9a\xb9\xfa\xbf\xcc\x08\xc7',  # noqa
+        'sha1': b'f\x15y+\xcb][\\\n\xf28\xb2\x0c_P[\xc8\x89Hk',
+        'sha1_git': b'\xc2\xae\xfa\xba\xfa\xa6B\x9b^\xf9Z\xf5\x14\x0cna\xb0\xef\x8b',  # noqa
+        'sha256': b"\x77\x022\xedZN\x84\xe8za\xf8'(oA\xc9k\xb1\x80c\x80\xe7J\x06\xea\xd2\xd5\xbeB\x19\xb8\xce",  # noqa
+        'length': 50,
+        'data': b'temp file for testing content storage conversion 2',
+        'status': 'visible',
+    }
+
+    sample_directory = {
+        'id': b'f\x15y+\xcb][\\\n\xf28\xb2\x0c_P[\xc8\x89Hk',
+        'entries': []
+    }
+
+    sample_person = {
+        'name': b'John Doe',
+        'email': b'john.doe@institute.org',
+        'fullname': b'John Doe <john.doe@institute.org>'
+    }
+
+    sample_revision = {
+        'id': b'f\x15y+\xcb][\\\n\xf28\xb2\x0c_P[\xc8\x89Hk',
+        'message': b'something',
+        'author': sample_person,
+        'committer': sample_person,
+        'date': 1567591673,
+        'committer_date': 1567591673,
+        'type': 'tar',
+        'directory': b'\xc2\xae\xfa\xba\xfa\xa6B\x9b^\xf9Z\xf5\x14\x0cna\xb0\xef\x8b',  # noqa
+        'synthetic': False,
+        'metadata': {},
+        'parents': [],
+    }
+
+    return {
+        'content': [sample_content, sample_content2],
+        'person': [sample_person],
+        'directory': [sample_directory],
+        'revision': [sample_revision],
+    }
diff --git a/swh/storage/__init__.py b/swh/storage/__init__.py
--- a/swh/storage/__init__.py
+++ b/swh/storage/__init__.py
@@ -13,7 +13,7 @@
     pass
 
 
-STORAGE_IMPLEMENTATION = {'local', 'remote', 'memory'}
+STORAGE_IMPLEMENTATION = {'local', 'remote', 'memory', 'filter'}
 
 
 def get_storage(cls, args):
@@ -22,7 +22,7 @@
 
     Args:
         storage (dict): dictionary with keys:
-        - cls (str): storage's class, either local, remote, memory
+        - cls (str): storage's class, either local, remote, memory, filter
         - args (dict): dictionary with keys
 
     Returns:
@@ -42,5 +42,7 @@
         from .storage import Storage
     elif cls == 'memory':
         from .in_memory import Storage
+    elif cls == 'filter':
+        from .filter import FilteringProxyStorage as Storage
 
     return Storage(**args)
diff --git a/swh/storage/filter.py b/swh/storage/filter.py
new file mode 100644
--- /dev/null
+++ b/swh/storage/filter.py
@@ -0,0 +1,116 @@
+# Copyright (C) 2019 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
+
+
+from typing import Dict, Generator, Sequence, Set
+
+from swh.storage import get_storage
+
+
+class FilteringProxyStorage:
+    """Filtering Storage implementation. This is in charge of transparently
+       filtering out known objects prior to adding them to storage.
+
+    Sample configuration use case for filtering storage:
+
+    .. code-block: yaml
+
+        storage:
+          cls: filter
+          args:
+            storage:
+              cls: remote
+              args: http://storage.internal.staging.swh.network:5002/
+
+    """
+    def __init__(self, storage):
+        self.storage = get_storage(**storage)
+        self.objects_seen = {
+            'content': set(),    # set of content hashes (sha256) seen
+            'directory': set(),
+            'revision': set(),
+        }
+
+    def __getattr__(self, key):
+        return getattr(self.storage, key)
+
+    def content_add(self, content: Sequence[Dict]) -> Dict:
+        contents = list(content)
+        contents_to_add = self._filter_missing_contents(contents)
+        return self.storage.content_add(
+            x for x in contents if x['sha256'] in contents_to_add
+        )
+
+    def directory_add(self, directories: Sequence[Dict]) -> Dict:
+        directories = list(directories)
+        missing_ids = self._filter_missing_ids(
+            'directory',
+            (d['id'] for d in directories)
+        )
+        return self.storage.directory_add(
+            d for d in directories if d['id'] in missing_ids
+        )
+
+    def revision_add(self, revisions):
+        revisions = list(revisions)
+        missing_ids = self._filter_missing_ids(
+            'revision',
+            (d['id'] for d in revisions)
+        )
+        return self.storage.revision_add(
+            r for r in revisions if r['id'] in missing_ids
+        )
+
+    def _filter_missing_contents(
+            self, content_hashes: Sequence[Dict]) -> Set[bytes]:
+        """Return only the content keys missing from swh
+
+        Args:
+            content_hashes: List of sha256 to check for existence in swh
+                storage
+
+        """
+        objects_seen = self.objects_seen['content']
+        missing_hashes = []
+        for hashes in content_hashes:
+            if hashes['sha256'] in objects_seen:
+                continue
+            objects_seen.add(hashes['sha256'])
+            missing_hashes.append(hashes)
+
+        return set(self.storage.content_missing(
+            missing_hashes,
+            key_hash='sha256',
+        ))
+
+    def _filter_missing_ids(
+            self,
+            object_type: str,
+            ids: Generator[bytes, None, None]) -> Set[bytes]:
+        """Filter missing ids from the storage for a given object type.
+
+        Args:
+            object_type: object type to use {revision, directory}
+            ids: Sequence of object_type ids
+
+        Returns:
+            Missing ids from the storage for object_type
+
+        """
+        objects_seen = self.objects_seen[object_type]
+        missing_ids = []
+        for id in ids:
+            if id in objects_seen:
+                continue
+            objects_seen.add(id)
+            missing_ids.append(id)
+
+        fn_by_object_type = {
+            'revision': self.storage.revision_missing,
+            'directory': self.storage.directory_missing,
+        }
+
+        fn = fn_by_object_type[object_type]
+        return set(fn(missing_ids))
diff --git a/swh/storage/tests/test_filter.py b/swh/storage/tests/test_filter.py
new file mode 100644
--- /dev/null
+++ b/swh/storage/tests/test_filter.py
@@ -0,0 +1,74 @@
+# Copyright (C) 2019 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
+
+
+from swh.storage.filter import FilteringProxyStorage
+
+
+def test_filtering_proxy_storage_content(sample_data):
+    sample_content = sample_data['content'][0]
+    storage = FilteringProxyStorage(storage={'cls': 'memory', 'args': {}})
+
+    content = next(storage.content_get([sample_content['sha1']]))
+    assert not content
+
+    s = storage.content_add([sample_content])
+    assert s == {
+        'content:add': 1,
+        'content:add:bytes': 48,
+        'skipped_content:add': 0
+    }
+
+    content = next(storage.content_get([sample_content['sha1']]))
+    assert content is not None
+
+    s = storage.content_add([sample_content])
+    assert s == {
+        'content:add': 0,
+        'content:add:bytes': 0,
+        'skipped_content:add': 0
+    }
+
+
+def test_filtering_proxy_storage_revision(sample_data):
+    sample_revision = sample_data['revision'][0]
+    storage = FilteringProxyStorage(storage={'cls': 'memory', 'args': {}})
+
+    revision = next(storage.revision_get([sample_revision['id']]))
+    assert not revision
+
+    s = storage.revision_add([sample_revision])
+    assert s == {
+        'revision:add': 1,
+    }
+
+    revision = next(storage.revision_get([sample_revision['id']]))
+    assert revision is not None
+
+    s = storage.revision_add([sample_revision])
+    assert s == {
+        'revision:add': 0,
+    }
+
+
+def test_filtering_proxy_storage_directory(sample_data):
+    sample_directory = sample_data['directory'][0]
+    storage = FilteringProxyStorage(storage={'cls': 'memory', 'args': {}})
+
+    directory = next(storage.directory_missing([sample_directory['id']]))
+    assert directory
+
+    s = storage.directory_add([sample_directory])
+    assert s == {
+        'directory:add': 1,
+    }
+
+    directory = list(storage.directory_missing([sample_directory['id']]))
+    assert not directory
+
+    s = storage.directory_add([sample_directory])
+    assert s == {
+        'directory:add': 0,
+    }
diff --git a/swh/storage/tests/test_init.py b/swh/storage/tests/test_init.py
--- a/swh/storage/tests/test_init.py
+++ b/swh/storage/tests/test_init.py
@@ -10,6 +10,7 @@
 from swh.storage.api.client import RemoteStorage
 # from swh.storage.storage import Storage as DbStorage
 from swh.storage.in_memory import Storage as MemoryStorage
+from swh.storage.filter import FilteringProxyStorage
 
 
 def test_get_storage():
@@ -26,6 +27,9 @@
             #         'cls': 'local', 'args': {}
             #     }
             # }),
+            ('filter', FilteringProxyStorage, {'storage': {
+                'cls': 'memory', 'args': {}}
+            })
     ]:
         actual_storage = get_storage(cls, args=dummy_args)
         assert actual_storage is not None