diff --git a/swh/search/elasticsearch.py b/swh/search/elasticsearch.py
--- a/swh/search/elasticsearch.py
+++ b/swh/search/elasticsearch.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2019-2021  The Software Heritage developers
+# Copyright (C) 2019-2022  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
diff --git a/swh/search/in_memory.py b/swh/search/in_memory.py
--- a/swh/search/in_memory.py
+++ b/swh/search/in_memory.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2019-2021  The Software Heritage developers
+# Copyright (C) 2019-2022  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
@@ -341,7 +341,7 @@
 
             hits = filter(predicate, hits)
 
-        if not url_pattern and not metadata_pattern:
+        if url_pattern is None and metadata_pattern is None:
             raise ValueError(
                 "At least one of url_pattern and metadata_pattern must be provided."
             )
diff --git a/swh/search/interface.py b/swh/search/interface.py
--- a/swh/search/interface.py
+++ b/swh/search/interface.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2020-2021  The Software Heritage developers
+# Copyright (C) 2020-2022  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
@@ -86,10 +86,11 @@
 
         Args:
             query: Find origins according the queries written as per the
-                swh-search query language syntax.
-            url_pattern: Part of the URL to search for
-            metadata_pattern: Keywords to look for
-            (across all the fields of intrinsic_metadata)
+                swh-search query language syntax, if empty return all origins
+            url_pattern: Part of the URL to search for, if empty and no filter
+                parameters used return all origins
+            metadata_pattern: Keywords to look for (across all the fields of
+                intrinsic_metadata)
             with_visit: Whether origins with no visits are to be filtered out
             visit_types: Only origins having any of the provided visit types
                 (e.g. git, svn, pypi) will be returned
diff --git a/swh/search/tests/test_search.py b/swh/search/tests/test_search.py
--- a/swh/search/tests/test_search.py
+++ b/swh/search/tests/test_search.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2019-2021  The Software Heritage developers
+# Copyright (C) 2019-2022  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
@@ -1257,3 +1257,30 @@
         self.search.flush()
 
         assert self.search.visit_types_count() == Counter(git=1, hg=2, svn=3)
+
+    def test_origin_search_empty_url_pattern(self):
+        origins = [
+            {"url": "http://foobar.baz", "visit_types": ["git"]},
+            {"url": "http://barbaz.qux", "visit_types": ["svn"]},
+            {"url": "http://qux.quux", "visit_types": ["hg"]},
+        ]
+
+        self.search.origin_update(origins)
+        self.search.flush()
+
+        # should match all origins
+        actual_page = self.search.origin_search(url_pattern="")
+        assert actual_page.next_page_token is None
+        results = [r["url"] for r in actual_page.results]
+        expected_results = [origin["url"] for origin in origins]
+        assert sorted(results) == sorted(expected_results)
+
+        # should match all origins with visit type
+        for origin in origins:
+            actual_page = self.search.origin_search(
+                url_pattern="", visit_types=origin["visit_types"]
+            )
+            assert actual_page.next_page_token is None
+            results = [r["url"] for r in actual_page.results]
+            expected_results = [origin["url"]]
+            assert results == expected_results
diff --git a/swh/search/tests/test_translator.py b/swh/search/tests/test_translator.py
--- a/swh/search/tests/test_translator.py
+++ b/swh/search/tests/test_translator.py
@@ -1,10 +1,8 @@
-# Copyright (C) 2021  The Software Heritage developers
+# Copyright (C) 2021-2022  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 swh.search.translator import Translator
 from swh.search.utils import get_expansion
 
@@ -16,8 +14,7 @@
 
 def test_empty_query():
     query = ""
-    with pytest.raises(Exception):
-        _test_results(query, {})
+    _test_results(query, {"filters": {"match_all": {}}})
 
 
 def test_conjunction_operators():
diff --git a/swh/search/translator.py b/swh/search/translator.py
--- a/swh/search/translator.py
+++ b/swh/search/translator.py
@@ -41,14 +41,17 @@
         self.query = ""
 
     def parse_query(self, query):
-        self.query = query.encode()
-        tree = self.parser.parse(self.query)
-        self.query_node = tree.root_node
+        if query:
+            self.query = query.encode()
+            tree = self.parser.parse(self.query)
+            self.query_node = tree.root_node
 
-        if self.query_node.has_error:
-            raise SearchQuerySyntaxError("Invalid query")
+            if self.query_node.has_error:
+                raise SearchQuerySyntaxError("Invalid query")
 
-        return self._traverse(self.query_node)
+            return self._traverse(self.query_node)
+        else:
+            return {"filters": {"match_all": {}}}
 
     def _traverse(self, node):
         if len(node.children) == 3 and node.children[1].type == "filters":