diff --git a/swh/scanner/cli.py b/swh/scanner/cli.py
--- a/swh/scanner/cli.py
+++ b/swh/scanner/cli.py
@@ -142,32 +142,50 @@
     type=click.Choice(["auto", "bfs", "greedybfs", "filepriority", "dirpriority"]),
     help="The scan policy.",
 )
+@click.option(
+    "-e",
+    "--extra-info",
+    "extra_info",
+    multiple=True,
+    type=click.Choice(["origin"]),
+    help="Add selected additional information about known software artifacts.",
+)
 @click.pass_context
-def scan(ctx, root_path, api_url, patterns, out_fmt, interactive, policy):
+def scan(ctx, root_path, api_url, patterns, out_fmt, interactive, policy, extra_info):
     """Scan a source code project to discover files and directories already
     present in the archive.
 
     The source code project can be checked using different policies that can be set
-    using the -p/--policy option:
-
-    auto: it selects the best policy based on the source code, for codebase(s) with
-    less than 1000 file/dir contents all the nodes will be queried.
-
-    bfs: scan the source code in the BFS order, checking unknown directories only.
-
-    greedybfs: same as "bfs" policy, but lookup the status of source code artifacts in
-    chunks, in order to minimize the number of Web API round-trips with the archive.
-
-    filepriority: scan all the source code file contents, checking only unset
-    directories. (useful if the codebase contains a lot of source files)
-
-    dirpriority: scan all the source code directories and check only unknown
-    directory contents.
-    """
+    using the -p/--policy option:\n
+    \b
+      auto: it selects the best policy based on the source code, for codebase(s)
+      with less than 1000 file/dir contents all the nodes will be queried.
+
+      bfs: scan the source code in the BFS order, checking unknown directories only.
+
+    \b
+      greedybfs: same as "bfs" policy, but lookup the status of source code artifacts
+      in chunks, in order to minimize the number of Web API round-trips with the
+      archive.
+
+    \b
+      filepriority: scan all the source code file contents, checking only unset
+      directories. (useful if the codebase contains a lot of source files)
+
+      dirpriority: scan all the source code directories and check only unknown
+      directory contents.
+
+    Other information about software artifacts could be specified with the -e/
+    --extra-info option:\n
+    \b
+      origin: search the origin url of each source code files/dirs using the in-memory
+      compressed graph.
+"""
     import swh.scanner.scanner as scanner
 
     config = setup_config(ctx, api_url)
-    scanner.scan(config, root_path, patterns, out_fmt, interactive, policy)
+    extra_info = set(extra_info)
+    scanner.scan(config, root_path, patterns, out_fmt, interactive, policy, extra_info)
 
 
 @scanner.group("db", help="Manage local knowledge base for swh-scanner")
diff --git a/swh/scanner/client.py b/swh/scanner/client.py
new file mode 100644
--- /dev/null
+++ b/swh/scanner/client.py
@@ -0,0 +1,98 @@
+# Copyright (C) 2021 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
+
+"""
+Minimal async web client for the Software Heritage Web API.
+
+This module could be removed when
+`T2635 <https://forge.softwareheritage.org/T2635>` is implemented.
+"""
+
+import asyncio
+import itertools
+from typing import Any, Dict, List, Optional
+
+import aiohttp
+
+from swh.model.identifiers import CoreSWHID
+
+from .exceptions import error_response
+
+# Maximum number of SWHIDs that can be requested by a single call to the
+# Web API endpoint /known/
+QUERY_LIMIT = 1000
+
+KNOWN_EP = "known/"
+GRAPH_RANDOMWALK_EP = "graph/randomwalk/"
+
+
+class Client:
+    """Manage requests to the Software Heritage Web API.
+    """
+
+    def __init__(self, api_url: str, session: aiohttp.ClientSession):
+        self.api_url = api_url
+        self.session = session
+
+    async def get_origin(self, swhid: CoreSWHID) -> Optional[Any]:
+        """Walk the compressed graph to discover the origin of a given swhid
+        """
+        endpoint = (
+            f"{self.api_url}{GRAPH_RANDOMWALK_EP}{str(swhid)}/ori/?direction="
+            f"backward&limit=-1&resolve_origins=true"
+        )
+        res = None
+        async with self.session.get(endpoint) as resp:
+            if resp.status == 200:
+                res = await resp.text()
+                res = res.rstrip()
+                return res
+            if resp.status != 404:
+                error_response(resp.reason, resp.status, endpoint)
+
+        return res
+
+    async def known(self, swhids: List[CoreSWHID]) -> Dict[str, Dict[str, bool]]:
+        """API Request to get information about the SoftWare Heritage persistent
+        IDentifiers (SWHIDs) given in input.
+
+        Args:
+            swhids: a list of CoreSWHID instances
+            api_url: url for the API request
+
+        Returns:
+            A dictionary with:
+
+            key:
+                string SWHID searched
+            value:
+                value['known'] = True if the SWHID is found
+                value['known'] = False if the SWHID is not found
+
+        """
+        endpoint = self.api_url + KNOWN_EP
+        requests = []
+
+        def get_chunk(swhids):
+            for i in range(0, len(swhids), QUERY_LIMIT):
+                yield swhids[i : i + QUERY_LIMIT]
+
+        async def make_request(swhids):
+            swhids = [str(swhid) for swhid in swhids]
+            async with self.session.post(endpoint, json=swhids) as resp:
+                if resp.status != 200:
+                    error_response(resp.reason, resp.status, endpoint)
+
+                return await resp.json()
+
+        if len(swhids) > QUERY_LIMIT:
+            for swhids_chunk in get_chunk(swhids):
+                requests.append(asyncio.create_task(make_request(swhids_chunk)))
+
+            res = await asyncio.gather(*requests)
+            # concatenate list of dictionaries
+            return dict(itertools.chain.from_iterable(e.items() for e in res))
+        else:
+            return await make_request(swhids)
diff --git a/swh/scanner/data.py b/swh/scanner/data.py
--- a/swh/scanner/data.py
+++ b/swh/scanner/data.py
@@ -4,12 +4,16 @@
 # See top-level LICENSE file for more information
 
 from pathlib import Path
-from typing import Dict, Tuple
+from typing import Dict, Optional, Tuple
 
 from swh.model.exceptions import ValidationError
 from swh.model.from_disk import Directory
 from swh.model.identifiers import CONTENT, DIRECTORY, CoreSWHID
 
+from .client import Client
+
+SUPPORTED_INFO = {"known", "origin"}
+
 
 class MerkleNodeInfo(dict):
     """Store additional information about Merkle DAG nodes, using SWHIDs as keys"""
@@ -27,6 +31,45 @@
         super(MerkleNodeInfo, self).__setitem__(key, value)
 
 
+def init_merkle_node_info(source_tree: Directory, data: MerkleNodeInfo, info: set):
+    """Populate the MerkleNodeInfo with the SWHIDs of the given source tree and the
+       attributes that will be stored.
+    """
+    if not info:
+        raise Exception("Data initialization requires node attributes values.")
+    nodes_info: Dict[str, Optional[str]] = {}
+    for ainfo in info:
+        if ainfo in SUPPORTED_INFO:
+            nodes_info[ainfo] = None
+        else:
+            raise Exception(f"Information {ainfo} is not supported.")
+
+    for node in source_tree.iter_tree():
+        data[node.swhid()] = nodes_info.copy()  # type: ignore
+
+
+async def add_origin(source_tree: Directory, data: MerkleNodeInfo, client: Client):
+    """Store origin information about software artifacts retrieved from the Software
+       Heritage graph service.
+    """
+    queue = []
+    queue.append(source_tree)
+    while queue:
+        for node in queue.copy():
+            queue.remove(node)
+            node_ori = await client.get_origin(node.swhid())
+            if node_ori:
+                data[node.swhid()]["origin"] = node_ori
+                if node.object_type == DIRECTORY:
+                    for sub_node in node.iter_tree():
+                        data[sub_node.swhid()]["origin"] = node_ori  # type: ignore
+            else:
+                if node.object_type == DIRECTORY:
+                    children = [sub_node for sub_node in node.iter_tree()]
+                    children.remove(node)
+                    queue.extend(children)  # type: ignore
+
+
 def get_directory_data(
     root_path: str,
     source_tree: Directory,
diff --git a/swh/scanner/exceptions.py b/swh/scanner/exceptions.py
--- a/swh/scanner/exceptions.py
+++ b/swh/scanner/exceptions.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, Optional
+
 
 class InvalidObjectType(TypeError):
     pass
@@ -25,6 +27,6 @@
         return '"%s"' % self.args
 
 
-def error_response(reason: str, status_code: int, api_url: str):
+def error_response(reason: Optional[Any], status_code: int, api_url: str):
     error_msg = f"{status_code} {reason}: '{api_url}'"
     raise APIError(error_msg)
diff --git a/swh/scanner/output.py b/swh/scanner/output.py
--- a/swh/scanner/output.py
+++ b/swh/scanner/output.py
@@ -93,12 +93,13 @@
     def data_as_json(self):
         json = {}
         for node in self.source_tree.iter_tree():
-            node_known = self.nodes_data[node.swhid()]["known"]
             rel_path = os.path.relpath(
                 node.data[self.get_path_name(node)].decode(),
                 self.source_tree.data["path"].decode(),
             )
-            json[rel_path] = {"swhid": str(node.swhid()), "known": node_known}
+            json[rel_path] = {"swhid": str(node.swhid())}
+            for k, v in self.nodes_data[node.swhid()].items():
+                json[rel_path][k] = v
         return json
 
     def print_json(self):
diff --git a/swh/scanner/policy.py b/swh/scanner/policy.py
--- a/swh/scanner/policy.py
+++ b/swh/scanner/policy.py
@@ -4,68 +4,14 @@
 # See top-level LICENSE file for more information
 
 import abc
-import asyncio
-import itertools
-from typing import Dict, List, no_type_check
-
-import aiohttp
+from typing import no_type_check
 
 from swh.core.utils import grouper
 from swh.model.from_disk import Directory
-from swh.model.identifiers import CONTENT, DIRECTORY, CoreSWHID
+from swh.model.identifiers import CONTENT, DIRECTORY
 
+from .client import QUERY_LIMIT, Client
 from .data import MerkleNodeInfo
-from .exceptions import error_response
-
-# Maximum number of SWHIDs that can be requested by a single call to the
-# Web API endpoint /known/
-QUERY_LIMIT = 1000
-
-
-async def swhids_discovery(
-    swhids: List[CoreSWHID], session: aiohttp.ClientSession, api_url: str,
-) -> Dict[str, Dict[str, bool]]:
-    """API Request to get information about the SoftWare Heritage persistent
-    IDentifiers (SWHIDs) given in input.
-
-    Args:
-        swhids: a list of CoreSWHID instances
-        api_url: url for the API request
-
-    Returns:
-        A dictionary with:
-
-        key:
-            string SWHID searched
-        value:
-            value['known'] = True if the SWHID is found
-            value['known'] = False if the SWHID is not found
-
-    """
-    endpoint = api_url + "known/"
-    requests = []
-
-    def get_chunk(swhids):
-        for i in range(0, len(swhids), QUERY_LIMIT):
-            yield swhids[i : i + QUERY_LIMIT]
-
-    async def make_request(swhids):
-        swhids = [str(swhid) for swhid in swhids]
-        async with session.post(endpoint, json=swhids) as resp:
-            if resp.status != 200:
-                error_response(resp.reason, resp.status, endpoint)
-
-            return await resp.json()
-
-    if len(swhids) > QUERY_LIMIT:
-        for swhids_chunk in get_chunk(swhids):
-            requests.append(asyncio.create_task(make_request(swhids_chunk)))
-
-        res = await asyncio.gather(*requests)
-        # concatenate list of dictionaries
-        return dict(itertools.chain.from_iterable(e.items() for e in res))
-    else:
-        return await make_request(swhids)
 
 
 def source_size(source_tree: Directory):
@@ -83,15 +29,11 @@
     """representation of a source code project directory in the merkle tree"""
 
     def __init__(self, source_tree: Directory, data: MerkleNodeInfo):
-        self.data = data
         self.source_tree = source_tree
-        for node in source_tree.iter_tree():
-            self.data[node.swhid()] = {"known": None}  # type: ignore
+        self.data = data
 
     @abc.abstractmethod
-    async def run(
-        self, session: aiohttp.ClientSession, api_url: str,
-    ):
+    async def run(self, client: Client):
         """Scan a source code project"""
         raise NotImplementedError("Must implement run method")
 
@@ -102,15 +44,13 @@
        contents to known.
     """
 
-    async def run(
-        self, session: aiohttp.ClientSession, api_url: str,
-    ):
+    async def run(self, client: Client):
         queue = []
         queue.append(self.source_tree)
 
         while queue:
             swhids = [node.swhid() for node in queue]
-            swhids_res = await swhids_discovery(swhids, session, api_url)
+            swhids_res = await client.known(swhids)
             for node in queue.copy():
                 queue.remove(node)
                 self.data[node.swhid()]["known"] = swhids_res[str(node.swhid())][
@@ -132,13 +72,11 @@
        downstream contents of known directories to known.
     """
 
-    async def run(
-        self, session: aiohttp.ClientSession, api_url: str,
-    ):
+    async def run(self, client: Client):
         ssize = source_size(self.source_tree)
         seen = []
 
-        async for nodes_chunk in self.get_nodes_chunks(session, api_url, ssize):
+        async for nodes_chunk in self.get_nodes_chunks(client, ssize):
             for node in nodes_chunk:
                 seen.append(node)
                 if len(seen) == ssize:
@@ -151,9 +89,7 @@
                         self.data[sub_node.swhid()]["known"] = True
 
     @no_type_check
-    async def get_nodes_chunks(
-        self, session: aiohttp.ClientSession, api_url: str, ssize: int
-    ):
+    async def get_nodes_chunks(self, client: Client, ssize: int):
         """Query chunks of QUERY_LIMIT nodes at once in order to fill the Web API
            rate limit. It query all the nodes in the case the source code contains
            less than QUERY_LIMIT nodes.
@@ -162,7 +98,7 @@
         for nodes_chunk in grouper(nodes, QUERY_LIMIT):
             nodes_chunk = [n for n in nodes_chunk]
             swhids = [node.swhid() for node in nodes_chunk]
-            swhids_res = await swhids_discovery(swhids, session, api_url)
+            swhids_res = await client.known(swhids)
             for node in nodes_chunk:
                 swhid = node.swhid()
                 self.data[swhid]["known"] = swhids_res[str(swhid)]["known"]
@@ -177,9 +113,7 @@
     """
 
     @no_type_check
-    async def run(
-        self, session: aiohttp.ClientSession, api_url: str,
-    ):
+    async def run(self, client: Client):
         # get all the files
         all_contents = list(
             filter(
@@ -190,7 +124,7 @@
 
         # query the backend to get all file contents status
         cnt_swhids = [node.swhid() for node in all_contents]
-        cnt_status_res = await swhids_discovery(cnt_swhids, session, api_url)
+        cnt_status_res = await client.known(cnt_swhids)
         # set all the file contents status
         for cnt in all_contents:
             self.data[cnt.swhid()]["known"] = cnt_status_res[str(cnt.swhid())]["known"]
@@ -215,7 +149,7 @@
         for dir_ in unset_dirs:
             if self.data[dir_.swhid()]["known"] is None:
                 # update directory status
-                dir_status = await swhids_discovery([dir_.swhid()], session, api_url)
+                dir_status = await client.known([dir_.swhid()])
                 dir_known = dir_status[str(dir_.swhid())]["known"]
                 self.data[dir_.swhid()]["known"] = dir_known
                 if dir_known:
@@ -239,9 +173,7 @@
     """
 
     @no_type_check
-    async def run(
-        self, session: aiohttp.ClientSession, api_url: str,
-    ):
+    async def run(self, client: Client):
         # get all directory contents that have at least one file content
         unknown_dirs = list(
             filter(
@@ -253,7 +185,7 @@
 
         for dir_ in unknown_dirs:
             if self.data[dir_.swhid()]["known"] is None:
-                dir_status = await swhids_discovery([dir_.swhid()], session, api_url)
+                dir_status = await client.known([dir_.swhid()])
                 dir_known = dir_status[str(dir_.swhid())]["known"]
                 self.data[dir_.swhid()]["known"] = dir_known
                 # set all the downstream file contents to known
@@ -277,7 +209,7 @@
             )
         )
         empty_dirs_swhids = [n.swhid() for n in empty_dirs]
-        empty_dir_status = await swhids_discovery(empty_dirs_swhids, session, api_url)
+        empty_dir_status = await client.known(empty_dirs_swhids)
 
         # update status of directories that have no file contents
         for dir_ in empty_dirs:
@@ -294,9 +226,7 @@
             )
         )
         unknown_cnts_swhids = [n.swhid() for n in unknown_cnts]
-        unknown_cnts_status = await swhids_discovery(
-            unknown_cnts_swhids, session, api_url
-        )
+        unknown_cnts_status = await client.known(unknown_cnts_swhids)
 
         for cnt in unknown_cnts:
             self.data[cnt.swhid()]["known"] = unknown_cnts_status[str(cnt.swhid())][
@@ -322,11 +252,9 @@
     """
 
     @no_type_check
-    async def run(
-        self, session: aiohttp.ClientSession, api_url: str,
-    ):
+    async def run(self, client: Client):
         all_nodes = [node for node in self.source_tree.iter_tree()]
         all_swhids = [node.swhid() for node in all_nodes]
-        swhids_res = await swhids_discovery(all_swhids, session, api_url)
+        swhids_res = await client.known(all_swhids)
         for node in all_nodes:
             self.data[node.swhid()]["known"] = swhids_res[str(node.swhid())]["known"]
diff --git a/swh/scanner/scanner.py b/swh/scanner/scanner.py
--- a/swh/scanner/scanner.py
+++ b/swh/scanner/scanner.py
@@ -11,7 +11,8 @@
 from swh.model.cli import model_of_dir
 from swh.model.from_disk import Directory
 
-from .data import MerkleNodeInfo
+from .client import Client
+from .data import MerkleNodeInfo, add_origin, init_merkle_node_info
 from .output import Output
 from .policy import (
     QUERY_LIMIT,
@@ -24,13 +25,14 @@
 )
 
 
-async def run(config: Dict[str, Any], policy) -> None:
+async def run(
+    config: Dict[str, Any],
+    policy,
+    source_tree: Directory,
+    nodes_data: MerkleNodeInfo,
+    extra_info: set,
+) -> None:
     """Scan a given source code according to the policy given in input.
-
-    Args:
-        root: the root path to scan
-        api_url: url for the API request
-
     """
     api_url = config["web-api"]["url"]
 
@@ -40,7 +42,14 @@
         headers = {}
 
     async with aiohttp.ClientSession(headers=headers, trust_env=True) as session:
-        await policy.run(session, api_url)
+        client = Client(api_url, session)
+        for info in extra_info:
+            if info == "known":
+                await policy.run(client)
+            elif info == "origin":
+                await add_origin(source_tree, nodes_data, client)
+            else:
+                raise Exception(f"The information '{info}' cannot be retrieved")
 
 
 def get_policy_obj(source_tree: Directory, nodes_data: MerkleNodeInfo, policy: str):
@@ -69,16 +78,21 @@
     out_fmt: str,
     interactive: bool,
     policy: str,
+    extra_info: set,
 ):
     """Scan a source code project to discover files and directories already
     present in the archive"""
     converted_patterns = [pattern.encode() for pattern in exclude_patterns]
     source_tree = model_of_dir(root_path.encode(), converted_patterns)
+
     nodes_data = MerkleNodeInfo()
+    extra_info.add("known")
+    init_merkle_node_info(source_tree, nodes_data, extra_info)
+
     policy = get_policy_obj(source_tree, nodes_data, policy)
 
     loop = asyncio.get_event_loop()
-    loop.run_until_complete(run(config, policy))
+    loop.run_until_complete(run(config, policy, source_tree, nodes_data, extra_info))
 
     out = Output(root_path, nodes_data, source_tree)
     if interactive:
diff --git a/swh/scanner/tests/data.py b/swh/scanner/tests/data.py
--- a/swh/scanner/tests/data.py
+++ b/swh/scanner/tests/data.py
@@ -3,12 +3,17 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
-correct_api_response = {
+correct_known_api_response = {
     "swh:1:dir:17d207da3804cc60a77cba58e76c3b2f767cb112": {"known": False},
     "swh:1:dir:01fa282bb80be5907505d44b4692d3fa40fad140": {"known": True},
     "swh:1:dir:4b825dc642cb6eb9a060e54bf8d69288fbee4904": {"known": True},
 }
 
+correct_origin_api_response = "https://bitbucket.org/chubbymaggie/bindead.git"
+
+sample_folder_root_swhid = "swh:1:dir:0a7b61ef5780b03aa274d11069564980246445ce"
+fake_origin = {sample_folder_root_swhid: correct_origin_api_response}
+
 present_swhids = [
     "swh:1:cnt:7c4c57ba9ff496ad179b8f65b1d286edbda34c9a",  # quotes.md
     "swh:1:cnt:68769579c3eaadbe555379b9c3538e6628bae1eb",  # some-binary
diff --git a/swh/scanner/tests/flask_api.py b/swh/scanner/tests/flask_api.py
--- a/swh/scanner/tests/flask_api.py
+++ b/swh/scanner/tests/flask_api.py
@@ -3,12 +3,12 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
-from flask import Flask, request
+from flask import Flask, abort, request
 
 from swh.scanner.exceptions import LargePayloadExc
 from swh.scanner.policy import QUERY_LIMIT
 
-from .data import unknown_swhids
+from .data import fake_origin, unknown_swhids
 
 
 def create_app(tmp_requests):
@@ -38,4 +38,11 @@
 
         return res
 
+    @app.route("/graph/randomwalk/<swhid>/ori/", methods=["GET"])
+    def randomwalk(swhid):
+        if swhid in fake_origin.keys():
+            return fake_origin[swhid]
+        else:
+            abort(404)
+
     return app
diff --git a/swh/scanner/tests/test_client.py b/swh/scanner/tests/test_client.py
new file mode 100644
--- /dev/null
+++ b/swh/scanner/tests/test_client.py
@@ -0,0 +1,58 @@
+# Copyright (C) 2021 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 pytest
+
+from swh.model.identifiers import CoreSWHID
+from swh.scanner.client import Client
+from swh.scanner.exceptions import APIError
+
+from .data import correct_known_api_response, correct_origin_api_response
+
+AIO_URL = "http://example.org/api/"
+KNOWN_URL = f"{AIO_URL}known/"
+ORIGIN_URL = f"{AIO_URL}graph/randomwalk/"
+
+
+def test_client_known_correct_api_request(mock_aioresponse, event_loop, aiosession):
+    mock_aioresponse.post(
+        KNOWN_URL,
+        status=200,
+        content_type="application/json",
+        body=json.dumps(correct_known_api_response),
+    )
+
+    client = Client(AIO_URL, aiosession)
+    actual_result = event_loop.run_until_complete(client.known([]))
+
+    assert correct_known_api_response == actual_result
+
+
+def test_client_known_raise_apierror(mock_aioresponse, event_loop, aiosession):
+    mock_aioresponse.post(KNOWN_URL, content_type="application/json", status=413)
+
+    client = Client(AIO_URL, aiosession)
+    with pytest.raises(APIError):
+        event_loop.run_until_complete(client.known([]))
+
+
+def test_client_get_origin_correct_api_request(
+    mock_aioresponse, event_loop, aiosession
+):
+    origin_url = (
+        f"{ORIGIN_URL}swh:1:dir:01fa282bb80be5907505d44b4692d3fa40fad140/ori"
+        f"/?direction=backward&limit=-1&resolve_origins=true"
+    )
+    mock_aioresponse.get(
+        origin_url, status=200, body=correct_origin_api_response,
+    )
+
+    client = Client(AIO_URL, aiosession)
+    swhid = CoreSWHID.from_string("swh:1:dir:01fa282bb80be5907505d44b4692d3fa40fad140")
+    actual_result = event_loop.run_until_complete(client.get_origin(swhid))
+
+    assert correct_origin_api_response == actual_result
diff --git a/swh/scanner/tests/test_data.py b/swh/scanner/tests/test_data.py
--- a/swh/scanner/tests/test_data.py
+++ b/swh/scanner/tests/test_data.py
@@ -5,16 +5,22 @@
 
 from pathlib import Path
 
+from flask import url_for
 import pytest
 
 from swh.model.exceptions import ValidationError
+from swh.scanner.client import Client
 from swh.scanner.data import (
     MerkleNodeInfo,
+    add_origin,
     directory_content,
     get_directory_data,
     has_dirs,
+    init_merkle_node_info,
 )
 
+from .data import fake_origin
+
 
 def test_merkle_node_data_wrong_args():
     nodes_data = MerkleNodeInfo()
@@ -26,6 +32,29 @@
         nodes_data["swh:1:dir:17d207da3804cc60a77cba58e76c3b2f767cb112"] = "wrong value"
 
 
+def test_init_merkle_supported_node_info(source_tree):
+    nodes_data = MerkleNodeInfo()
+    init_merkle_node_info(source_tree, nodes_data, {"known", "origin"})
+    for _, node_attrs in nodes_data.items():
+        assert "known" and "origin" in node_attrs.keys()
+
+
+def test_init_merkle_not_supported_node_info(source_tree):
+    nodes_data = MerkleNodeInfo()
+    with pytest.raises(Exception):
+        init_merkle_node_info(source_tree, nodes_data, {"unsupported_info"})
+
+
+def test_add_origin(event_loop, live_server, aiosession, source_tree, nodes_data):
+    api_url = url_for("index", _external=True)
+    init_merkle_node_info(source_tree, nodes_data, {"known", "origin"})
+    client = Client(api_url, aiosession)
+
+    event_loop.run_until_complete(add_origin(source_tree, nodes_data, client))
+    for node, attrs in nodes_data.items():
+        assert attrs["origin"] == fake_origin[str(source_tree.swhid())]
+
+
 def test_get_directory_data(source_tree, nodes_data):
     root = Path(source_tree.data["path"].decode())
     dirs_data = get_directory_data(root, source_tree, nodes_data)
diff --git a/swh/scanner/tests/test_policy.py b/swh/scanner/tests/test_policy.py
--- a/swh/scanner/tests/test_policy.py
+++ b/swh/scanner/tests/test_policy.py
@@ -3,51 +3,21 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
-import json
 
 from flask import url_for
 import pytest
 
 from swh.model.identifiers import CONTENT, CoreSWHID, ObjectType
-from swh.scanner.data import MerkleNodeInfo
-from swh.scanner.exceptions import APIError
+from swh.scanner.client import Client
+from swh.scanner.data import MerkleNodeInfo, init_merkle_node_info
 from swh.scanner.policy import (
     DirectoryPriority,
     FilePriority,
     GreedyBFS,
     LazyBFS,
     source_size,
-    swhids_discovery,
 )
 
-from .data import correct_api_response
-
-aio_url = "http://example.org/api/known/"
-
-
-def test_scanner_correct_api_request(mock_aioresponse, event_loop, aiosession):
-    mock_aioresponse.post(
-        aio_url,
-        status=200,
-        content_type="application/json",
-        body=json.dumps(correct_api_response),
-    )
-
-    actual_result = event_loop.run_until_complete(
-        swhids_discovery([], aiosession, "http://example.org/api/")
-    )
-
-    assert correct_api_response == actual_result
-
-
-def test_scanner_raise_apierror(mock_aioresponse, event_loop, aiosession):
-    mock_aioresponse.post(aio_url, content_type="application/json", status=413)
-
-    with pytest.raises(APIError):
-        event_loop.run_until_complete(
-            swhids_discovery([], aiosession, "http://example.org/api/")
-        )
-
 
 def test_scanner_directory_priority_has_contents(source_tree):
     nodes_data = MerkleNodeInfo()
@@ -69,8 +39,10 @@
     api_url = url_for("index", _external=True)
 
     nodes_data = MerkleNodeInfo()
+    init_merkle_node_info(source_tree_policy, nodes_data, {"known"})
     policy = LazyBFS(source_tree_policy, nodes_data)
-    event_loop.run_until_complete(policy.run(aiosession, api_url))
+    client = Client(api_url, aiosession)
+    event_loop.run_until_complete(policy.run(client))
 
     backend_swhids_requests = get_backend_swhids_order(tmp_requests)
 
@@ -105,8 +77,10 @@
     api_url = url_for("index", _external=True)
 
     nodes_data = MerkleNodeInfo()
+    init_merkle_node_info(source_tree_policy, nodes_data, {"known"})
     policy = DirectoryPriority(source_tree_policy, nodes_data)
-    event_loop.run_until_complete(policy.run(aiosession, api_url))
+    client = Client(api_url, aiosession)
+    event_loop.run_until_complete(policy.run(client))
 
     backend_swhids_requests = get_backend_swhids_order(tmp_requests)
 
@@ -124,8 +98,10 @@
     api_url = url_for("index", _external=True)
 
     nodes_data = MerkleNodeInfo()
+    init_merkle_node_info(source_tree_policy, nodes_data, {"known"})
     policy = FilePriority(source_tree_policy, nodes_data)
-    event_loop.run_until_complete(policy.run(aiosession, api_url))
+    client = Client(api_url, aiosession)
+    event_loop.run_until_complete(policy.run(client))
 
     backend_swhids_requests = get_backend_swhids_order(tmp_requests)
 
@@ -143,8 +119,10 @@
     api_url = url_for("index", _external=True)
 
     nodes_data = MerkleNodeInfo()
+    init_merkle_node_info(big_source_tree, nodes_data, {"known"})
     policy = GreedyBFS(big_source_tree, nodes_data)
-    event_loop.run_until_complete(policy.run(aiosession, api_url))
+    client = Client(api_url, aiosession)
+    event_loop.run_until_complete(policy.run(client))
 
     backend_swhids_requests = get_backend_swhids_order(tmp_requests)
 
@@ -157,11 +135,13 @@
     api_url = url_for("index", _external=True)
 
     nodes_data = MerkleNodeInfo()
+    init_merkle_node_info(big_source_tree, nodes_data, {"known"})
     policy = GreedyBFS(big_source_tree, nodes_data)
+    client = Client(api_url, aiosession)
     chunks = [
         n_chunk
         async for n_chunk in policy.get_nodes_chunks(
-            aiosession, api_url, source_size(big_source_tree)
+            client, source_size(big_source_tree)
         )
     ]
     assert len(chunks) == 2
diff --git a/swh/scanner/tests/test_scanner.py b/swh/scanner/tests/test_scanner.py
--- a/swh/scanner/tests/test_scanner.py
+++ b/swh/scanner/tests/test_scanner.py
@@ -6,7 +6,7 @@
 from flask import url_for
 import pytest
 
-from swh.scanner.data import MerkleNodeInfo
+from swh.scanner.data import MerkleNodeInfo, init_merkle_node_info
 from swh.scanner.policy import DirectoryPriority, FilePriority, LazyBFS, QueryAll
 from swh.scanner.scanner import get_policy_obj, run
 
@@ -33,8 +33,11 @@
     config = {"web-api": {"url": api_url, "auth-token": None}}
 
     nodes_data = MerkleNodeInfo()
+    init_merkle_node_info(source_tree, nodes_data, {"known"})
     policy = LazyBFS(source_tree, nodes_data)
-    event_loop.run_until_complete(run(config, policy))
+    event_loop.run_until_complete(
+        run(config, policy, source_tree, nodes_data, {"known"})
+    )
     for node in source_tree.iter_tree():
         if str(node.swhid()) in unknown_swhids:
             assert nodes_data[node.swhid()]["known"] is False
@@ -47,8 +50,11 @@
     config = {"web-api": {"url": api_url, "auth-token": None}}
 
     nodes_data = MerkleNodeInfo()
+    init_merkle_node_info(source_tree, nodes_data, {"known"})
     policy = FilePriority(source_tree, nodes_data)
-    event_loop.run_until_complete(run(config, policy))
+    event_loop.run_until_complete(
+        run(config, policy, source_tree, nodes_data, {"known"})
+    )
     for node in source_tree.iter_tree():
         if str(node.swhid()) in unknown_swhids:
             assert nodes_data[node.swhid()]["known"] is False
@@ -61,8 +67,11 @@
     config = {"web-api": {"url": api_url, "auth-token": None}}
 
     nodes_data = MerkleNodeInfo()
+    init_merkle_node_info(source_tree, nodes_data, {"known"})
     policy = DirectoryPriority(source_tree, nodes_data)
-    event_loop.run_until_complete(run(config, policy))
+    event_loop.run_until_complete(
+        run(config, policy, source_tree, nodes_data, {"known"})
+    )
     for node in source_tree.iter_tree():
         if str(node.swhid()) in unknown_swhids:
             assert nodes_data[node.swhid()]["known"] is False
@@ -75,8 +84,11 @@
     config = {"web-api": {"url": api_url, "auth-token": None}}
 
     nodes_data = MerkleNodeInfo()
+    init_merkle_node_info(source_tree, nodes_data, {"known"})
     policy = QueryAll(source_tree, nodes_data)
-    event_loop.run_until_complete(run(config, policy))
+    event_loop.run_until_complete(
+        run(config, policy, source_tree, nodes_data, {"known"})
+    )
     for node in source_tree.iter_tree():
         if str(node.swhid()) in unknown_swhids:
             assert nodes_data[node.swhid()]["known"] is False