diff --git a/API/Authentication/EventAuthentication.cs b/API/Authentication/EventAuthentication.cs
index b98d4a6..12ebb2a 100644
--- a/API/Authentication/EventAuthentication.cs
+++ b/API/Authentication/EventAuthentication.cs
@@ -41,5 +41,10 @@ namespace API.Authentication
 			return _grantManager.hasGrant(user.permissionId, EventGrantNames.CanDeleteAny) ||
 			       _grantManager.getULongValues(user.permissionId, EventGrantNames.CanDelete).Exists(x => x == model.id);
 		}
+		public bool canCheckSelfSignup(User user)
+		{
+			//todo grants
+			return true;
+		}
 	}
 }
diff --git a/API/Authentication/Interfaces/IEventAuthentication.cs b/API/Authentication/Interfaces/IEventAuthentication.cs
index 9681ea5..a73f42d 100644
--- a/API/Authentication/Interfaces/IEventAuthentication.cs
+++ b/API/Authentication/Interfaces/IEventAuthentication.cs
@@ -5,5 +5,6 @@ namespace API.Authentication.Interfaces
 {
 	public interface IEventAuthentication : IGenericAuthentication<EventDTO, Event>
 	{
+		bool canCheckSelfSignup(User user);
 	}
 }
diff --git a/API/Controllers/EventController.cs b/API/Controllers/EventController.cs
index 14e6638..03e3257 100644
--- a/API/Controllers/EventController.cs
+++ b/API/Controllers/EventController.cs
@@ -17,6 +17,7 @@ namespace API.Controllers
 		{
 		}
 		
+		//todo slow
 		[HttpGet("period")]
 		public virtual ActionResult<List<EventDTO>> getPeriod(DateTime start, DateTime end)
 		{
@@ -30,7 +31,7 @@ namespace API.Controllers
 		
 			List<EventDTO> dtos = [];
 		
-			Parallel.ForEach(result, item =>
+			Parallel.ForEach(result.ToList(), item =>
 			{
 				EventDTO dto = new EventDTO();
 				dto.adaptFromModel(item);
@@ -39,5 +40,19 @@ namespace API.Controllers
 		
 			return Ok(dtos);
 		}
+
+		[HttpGet("{eventId}/isSignedUp")]
+		public ActionResult<bool> isSignedUp(ulong eventId)
+		{
+			MUser? user = getUser(User);
+			if (user == null)
+				return Unauthorized();
+
+			bool? isSignedUp = Service.isSignedUp(user, eventId);
+			if (isSignedUp == null)
+				return Forbid();
+
+			return isSignedUp;
+		}
 	}
 }
diff --git a/API/Services/EventService.cs b/API/Services/EventService.cs
index 86495a5..29ee953 100644
--- a/API/Services/EventService.cs
+++ b/API/Services/EventService.cs
@@ -11,5 +11,13 @@ namespace API.Services
 		public EventService(ILogger<EventService> logger, SASGContext context, IEventAuthentication auth) : base(logger, context, auth)
 		{
 		}
+		
+		public bool? isSignedUp(User user, ulong eventId)
+		{
+			if (!_auth.canCheckSelfSignup(user))
+				return null;
+
+			return Context.Set<Signup>().Any(x => x.userId == user.id && x.eventId == eventId);
+		}
 	}
 }