diff --git a/.well-known/attribution-reporting/report-event-attribution b/.well-known/attribution-reporting/report-event-attribution
new file mode 100644
index 000000000000000..8ca40faaff7b727
--- /dev/null
+++ b/.well-known/attribution-reporting/report-event-attribution
@@ -0,0 +1,84 @@
+"""Endpoint to receive and return event-level attribution reports."""
+import json
+from typing import List, Optional, Tuple, TypedDict
+
+from wptserve.request import Request
+from wptserve.stash import Stash
+from wptserve.utils import isomorphic_decode, isomorphic_encode
+
+# Key used to access the reports in the stash. Since stash is unique per URL
+# path, we can use the same key for both event-level and aggregatable reports.
+STASH_KEY = "4691a2d7fca5430fb0f33b1bd8a9d388"
+
+Header = Tuple[str, str]
+Status = Tuple[int, str]
+Response = Tuple[Status, List[Header], str]
+
+CLEAR_STASH = isomorphic_encode("clear_stash")
+
+
+def handle_post_report(request: Request, headers: List[Header]) -> Response:
+  """Handles POST request for reports.
+
+  Retrieves the report from the request body and stores the report in the
+  stash. If clear_stash is specified in the query params, clears the stash.
+  """
+  if request.GET.get(CLEAR_STASH):
+    clear_stash(request.server.stash)
+    return (200, "OK"), headers, json.dumps({
+        "code": 200,
+        "message": "Stash successfully cleared.",
+    })
+  store_report(request.server.stash, request.body.decode("utf-8"))
+  return (201, "OK"), headers, json.dumps({
+      "code": 201,
+      "message": "Report successfully stored."
+  })
+
+
+def handle_get_reports(request: Request, headers: List[Header]) -> Response:
+  """Handles GET request for reports.
+
+  Retrieves and returns all reports from the stash.
+  """
+  reports = take_reports(request.server.stash)
+  return (200, "OK"), headers, json.dumps({
+      "code": 200,
+      "reports": reports,
+  })
+
+
+def store_report(stash: Stash, report: str) -> None:
+  """Stores the report in the stash. Report here is a JSON."""
+  reports = stash.take(STASH_KEY)
+  if not reports:
+    reports = []
+  reports.append(report)
+  stash.put(STASH_KEY, reports)
+  return None
+
+
+def take_reports(stash: Stash) -> List[str]:
+  """Takes all the reports from the stash and returns them."""
+  reports = stash.take(STASH_KEY)
+  if not reports:
+    reports = []
+  return reports
+
+
+def clear_stash(stash: Stash) -> None:
+  "Clears the stash."
+  stash.take(STASH_KEY)
+  return None
+
+
+def main(request, response):
+  headers = [("Content-Type", "application/json")]
+  if request.method == "POST":
+    return handle_post_report(request, headers)
+  if request.method == "GET":
+    return handle_get_reports(request, headers)
+  return (405, "Method Not Allowed"), headers, json.dumps({
+      "code": 405,
+      "message": "Only GET or POST methods are supported."
+  })