diff --git a/tools/validate-api-against-girder.py b/tools/validate-api-against-girder.py
new file mode 100644
index 000000000..8e203a081
--- /dev/null
+++ b/tools/validate-api-against-girder.py
@@ -0,0 +1,80 @@
+#!/usr/bin/env python3
+import click
+import requests
+
+from dandi.dandiapi import DandiAPIClient
+from dandi.dandiset import APIDandiset
+from dandi.girder import GirderCli
+
+
+def adhoc_list_girder(_id, client, prefix=""):
+    """Pure girder API has no recursive listing, so let's do it manually"""
+    res = list()
+    ret = []
+    for r in client.listItem(_id):
+        assert r.get("_modelType", None) == "item"
+        f = list(client.listFile(r["_id"]))
+        if len(f) == 0:
+            print(f"  Empty item with prefix={prefix}: {r}")
+            continue
+        if len(f) != 1:
+            print("Multiple files for an item still found!")
+            print(f)
+            import pdb
+
+            pdb.set_trace()
+        else:
+            f = f[0]
+            assert f["size"] == r["size"]
+        yield (f"{prefix}{r['name']}", r["size"])
+
+    for r in client.listFolder(_id, "folder"):
+        assert r.get("_modelType", None) == "folder"
+        yield from adhoc_list_girder(r["_id"], client, f"{prefix}{r['name']}/")
+
+
+@click.command()
+def main():
+    g_client = GirderCli("http://3.19.164.171")
+    a_client = DandiAPIClient("https://api.dandiarchive.org/api")
+
+    with a_client.session():
+        g_client.dandi_authenticate()
+        # gather all dandisets known to girder: hardcoded _id for "drafts" collection
+        g_dandisets = list(
+            g_client.listFolder("5e59bb0af19e820ab6ea6c62", "collection")
+        )
+        for dandiset, girder_id in [(x["name"], x["_id"]) for x in g_dandisets]:
+            if dandiset != "000026":
+                continue
+            print(f"DANDI:{dandiset}", end="\t")
+            g_meta, g_assets_ = g_client.get_dandiset_and_assets(girder_id, "folder")
+            g_assets = list(g_assets_)
+            # harmonize and get only what we care about ATM - path and size,
+            # or otherwise we would need to query each asset for metadata
+            g_assets_h = set((a["path"].lstrip("/"), a["size"]) for a in g_assets)
+
+            # Yarik trusts nobody.  Two identical bugs are less likely!
+            g_assets_adhoc = set(adhoc_list_girder(girder_id, g_client))
+
+            if g_assets_h != g_assets_adhoc:
+                print("ad-hoc and dandi listing of girder differs!")
+                import pdb
+
+                pdb.set_trace()
+
+            a_meta, a_assets_ = a_client.get_dandiset_and_assets(dandiset, "draft")
+            a_assets = list(a_assets_)
+            a_assets_h = set((a["path"].lstrip("/"), a["size"]) for a in a_assets)
+
+            if a_assets_h != g_assets_h:
+                print("differs")
+                import pdb
+
+                pdb.set_trace()
+            else:
+                print(f"{len(a_assets)} assets the same")
+
+
+if __name__ == "__main__":
+    main()