diff --git a/doc/manual/shadow.rst b/doc/manual/shadow.rst
index 5e504b8785..d5e9f0d850 100644
--- a/doc/manual/shadow.rst
+++ b/doc/manual/shadow.rst
@@ -54,6 +54,20 @@ In the DOMjudge admin interface, go to the *External Contest Sources* page and
 create an external contest source. Select the contest to import into and enter
 the source you want to import from.
 
+Another alternative is to use these DOMjudge only keys in the `contest.yaml`::
+
+  shadow:
+    type: contest-api
+    source: http(s)://url_to_external_system/api/contests/<contest_id>
+    username: user_in_external_system
+    password: password_for_user
+
+or::
+
+  shadow:
+    type: contest-archive
+    source: /path/on/domjudge/filestem/to/clics/compliant/archive
+
 Running the event feed import command
 -------------------------------------
 
diff --git a/webapp/src/Service/ImportExportService.php b/webapp/src/Service/ImportExportService.php
index a642bbf883..61d53337d3 100644
--- a/webapp/src/Service/ImportExportService.php
+++ b/webapp/src/Service/ImportExportService.php
@@ -5,6 +5,7 @@
 use App\Entity\Configuration;
 use App\Entity\Contest;
 use App\Entity\ContestProblem;
+use App\Entity\ExternalContestSource;
 use App\Entity\Problem;
 use App\Entity\Role;
 use App\Entity\Team;
@@ -251,6 +252,22 @@ public function importContestData(mixed $data, ?string &$errorMessage = null, st
         }
 
         $this->em->persist($contest);
+
+        $shadow = $data['shadow'] ?? null;
+        if ($shadow) {
+            $externalSource = $this->em->getRepository(ExternalContestSource::class)->findOneBy(['contest' => $contest]) ?: new ExternalContestSource();
+            $externalSource->setContest($contest);
+            foreach ($shadow as $field => $value) {
+                // Overwrite the existing value if the property is defined in the data: $externalSource-setSource($data['shadow']['source'])
+                $fieldFunc = 'set'.ucwords($field);
+                $fieldArgs = [$value];
+                if (method_exists($externalSource, $fieldFunc)) {
+                    $externalSource->$fieldFunc(...$fieldArgs);
+                }
+            }
+            $this->em->persist($externalSource);
+        }
+
         $this->em->flush();
 
         $penaltyTime = $data['penalty_time'] ?? $data['penalty-time'] ?? $data['penalty'] ?? null;