diff --git a/webapp/src/Controller/API/AbstractApiController.php b/webapp/src/Controller/API/AbstractApiController.php
index 92eddb8569..06425c05e5 100644
--- a/webapp/src/Controller/API/AbstractApiController.php
+++ b/webapp/src/Controller/API/AbstractApiController.php
@@ -29,6 +29,16 @@ public function __construct(
         protected readonly EventLogService $eventLogService
     ) {}
 
+    /**
+     * Whether to filter out contests that haven't started yet in calls to getQueryBuilder
+     * without an explicit value set for $filterBeforeContest.
+     * Override in subclasses to change this behavior.
+     */
+    protected function shouldFilterBeforeContest(): bool
+    {
+        return true;
+    }
+
     /**
      * Get the query builder used for getting contests.
      *
diff --git a/webapp/src/Controller/API/ContestController.php b/webapp/src/Controller/API/ContestController.php
index 24f46b76c0..2dd5e8bc35 100644
--- a/webapp/src/Controller/API/ContestController.php
+++ b/webapp/src/Controller/API/ContestController.php
@@ -356,24 +356,24 @@ public function setProblemsetAction(Request $request, string $cid, ValidatorInte
     public function problemsetAction(Request $request, string $cid): Response
     {
         /** @var Contest|null $contest */
-        $contest = $this->getQueryBuilder($request)
+        $contest = $this->getQueryBuilder($request, filterBeforeContest: true)
             ->andWhere(sprintf('%s = :id', $this->getIdField()))
             ->setParameter('id', $cid)
             ->getQuery()
             ->getOneOrNullResult();
 
+        if ($contest === null) {
+            throw new NotFoundHttpException(sprintf('Object with ID \'%s\' not found', $cid));
+        }
+
         $hasAccess = $this->dj->checkrole('jury') ||
             $this->dj->checkrole('api_reader') ||
-            $contest?->getFreezeData()->started();
+            $contest->getFreezeData()->started();
 
         if (!$hasAccess) {
             throw new AccessDeniedHttpException();
         }
 
-        if ($contest === null) {
-            throw new NotFoundHttpException(sprintf('Object with ID \'%s\' not found', $cid));
-        }
-
         if (!$contest->getContestProblemsetType()) {
             throw new NotFoundHttpException(sprintf('Contest with ID \'%s\' has no problemset text', $cid));
         }
@@ -950,10 +950,18 @@ public function samplesDataZipAction(Request $request): Response
         return $this->dj->getSamplesZipForContest($contest);
     }
 
-    protected function getQueryBuilder(Request $request, bool $filterBeforeContest = true): QueryBuilder
+    protected function shouldFilterBeforeContest(): bool
+    {
+        return false;
+    }
+
+    protected function getQueryBuilder(Request $request, ?bool $filterBeforeContest = null): QueryBuilder
     {
         try {
-            return $this->getContestQueryBuilder($request->query->getBoolean('onlyActive', true), $filterBeforeContest);
+            return $this->getContestQueryBuilder(
+                $request->query->getBoolean('onlyActive', true),
+                $filterBeforeContest ?? $this->shouldFilterBeforeContest()
+            );
         } catch (TypeError) {
             throw new BadRequestHttpException('\'onlyActive\' must be a boolean.');
         }
diff --git a/webapp/tests/Unit/Controller/API/ContestControllerTest.php b/webapp/tests/Unit/Controller/API/ContestControllerTest.php
index ae937d858e..b853ce52d0 100644
--- a/webapp/tests/Unit/Controller/API/ContestControllerTest.php
+++ b/webapp/tests/Unit/Controller/API/ContestControllerTest.php
@@ -2,6 +2,7 @@
 
 namespace App\Tests\Unit\Controller\API;
 
+use App\DataFixtures\Test\DemoPreStartContestFixture;
 use App\Entity\Contest;
 
 class ContestControllerTest extends BaseTestCase
@@ -26,4 +27,48 @@ class ContestControllerTest extends BaseTestCase
     protected array $expectedAbsent = ['4242', 'nonexistent'];
 
     protected ?string $objectClassForExternalId = Contest::class;
+
+    /**
+     * Test that a contest that is activated but not yet started is visible in the list action for a team user.
+     */
+    public function testListShowsActivatedButNotStartedContest(): void
+    {
+        $this->loadFixture(DemoPreStartContestFixture::class);
+
+        $url = $this->helperGetEndpointURL($this->apiEndpoint);
+        // Use 'demo' user which has team role
+        $objects = $this->verifyApiJsonResponse('GET', $url, 200, 'demo');
+
+        self::assertIsArray($objects);
+        self::assertNotEmpty($objects, 'Contest list should not be empty');
+
+        // Find the demo contest in the response
+        $foundContest = null;
+        foreach ($objects as $contest) {
+            if ($contest['shortname'] === 'demo') {
+                $foundContest = $contest;
+                break;
+            }
+        }
+
+        self::assertNotNull($foundContest, 'Demo contest should be visible after activation even before start');
+        self::assertSame('Demo contest', $foundContest['formal_name']);
+    }
+
+    /**
+     * Test that a contest that is activated but not yet started is visible in the single action for a team user.
+     */
+    public function testSingleShowsActivatedButNotStartedContest(): void
+    {
+        $this->loadFixture(DemoPreStartContestFixture::class);
+
+        $contestId = $this->resolveEntityId(Contest::class, '1');
+        $url = $this->helperGetEndpointURL($this->apiEndpoint, $contestId);
+        // Use 'demo' user which has team role
+        $contest = $this->verifyApiJsonResponse('GET', $url, 200, 'demo');
+
+        self::assertIsArray($contest);
+        self::assertSame('Demo contest', $contest['formal_name']);
+        self::assertSame('demo', $contest['shortname']);
+    }
 }