diff --git a/src/Squidex/Areas/Api/Controllers/Schemas/Models/CreateSchemaDto.cs b/src/Squidex/Areas/Api/Controllers/Schemas/Models/CreateSchemaDto.cs
index b8109375f..1835ecc51 100644
--- a/src/Squidex/Areas/Api/Controllers/Schemas/Models/CreateSchemaDto.cs
+++ b/src/Squidex/Areas/Api/Controllers/Schemas/Models/CreateSchemaDto.cs
@@ -37,6 +37,11 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models
         /// </summary>
         public bool Publish { get; set; }
 
+        /// <summary>
+        /// Set to true to allow a single content item only.
+        /// </summary>
+        public bool Singleton { get; set; }
+
         public CreateSchema ToCommand()
         {
             var command = new CreateSchema();
diff --git a/src/Squidex/Areas/Api/Controllers/Schemas/Models/SchemaDto.cs b/src/Squidex/Areas/Api/Controllers/Schemas/Models/SchemaDto.cs
index 0c0869ede..54b0fd561 100644
--- a/src/Squidex/Areas/Api/Controllers/Schemas/Models/SchemaDto.cs
+++ b/src/Squidex/Areas/Api/Controllers/Schemas/Models/SchemaDto.cs
@@ -44,6 +44,11 @@ namespace Squidex.Areas.Api.Controllers.Schemas.Models
         /// </summary>
         public bool IsPublished { get; set; }
 
+        /// <summary>
+        /// Indicates if the schema is a singleton.
+        /// </summary>
+        public bool IsSingleton { get; set; }
+
         /// <summary>
         /// The user that has created the schema.
         /// </summary>