diff --git a/src/ApiResource/CategoryApiResource.php b/src/ApiResource/CategoryApiResource.php
new file mode 100644
index 0000000..96b7435
--- /dev/null
+++ b/src/ApiResource/CategoryApiResource.php
@@ -0,0 +1,20 @@
+<?php
+
+namespace App\ApiResource;
+
+use ApiPlatform\Doctrine\Orm\State\Options;
+use ApiPlatform\Metadata as API;
+use App\Entity\Category;
+use App\State\ApiResourceStateProvider;
+
+#[API\ApiResource(
+    shortName: 'Category',
+    stateOptions: new Options(entityClass: Category::class)
+)]
+#[API\GetCollection(provider: ApiResourceStateProvider::class)]
+#[API\Get(provider: ApiResourceStateProvider::class)]
+class CategoryApiResource
+{
+    #[API\ApiProperty(identifier: true)]
+    public string $id;
+}
diff --git a/src/ApiResource/Project/ProjectApiResource.php b/src/ApiResource/Project/ProjectApiResource.php
index bf0b121..34b3726 100644
--- a/src/ApiResource/Project/ProjectApiResource.php
+++ b/src/ApiResource/Project/ProjectApiResource.php
@@ -6,6 +6,7 @@ use ApiPlatform\Doctrine\Orm\Filter\SearchFilter;
 use ApiPlatform\Doctrine\Orm\State\Options;
 use ApiPlatform\Metadata as API;
 use App\ApiResource\Accounting\AccountingApiResource;
+use App\ApiResource\CategoryApiResource;
 use App\ApiResource\LocalizedApiResourceTrait;
 use App\ApiResource\Matchfunding\MatchCallSubmissionApiResource;
 use App\ApiResource\User\UserApiResource;
@@ -109,6 +110,8 @@ class ProjectApiResource
 
     /**
      * A list of the available categories most relevant to this Project.
+     *
+     * @var array<int, CategoryApiResource>
      */
     #[Assert\NotBlank()]
     #[API\ApiFilter(filterClass: SearchFilter::class, strategy: 'exact')]
diff --git a/src/OpenApi/RedocExtensionsTrait.php b/src/OpenApi/RedocExtensionsTrait.php
index a9fa08d..85589ad 100644
--- a/src/OpenApi/RedocExtensionsTrait.php
+++ b/src/OpenApi/RedocExtensionsTrait.php
@@ -37,6 +37,7 @@ trait RedocExtensionsTrait
                     'ProjectBudgetItem',
                     'ProjectUpdate',
                     'ProjectSupport',
+                    'Category',
                 ],
             ],
             [