diff --git a/schemas/ak.schema.json b/schemas/ak.schema.json
index f8b6711c63ee67121a89e48ec43984f89a736eab..bd5bc7aebc35158573615c5fe463b4bcc44ee4dc 100644
--- a/schemas/ak.schema.json
+++ b/schemas/ak.schema.json
@@ -33,7 +33,8 @@
           "description": "IDs of all AKs that should be scheduled before this AK"
         }
       },
-      "required": ["conflicts", "dependencies"]
+      "required": ["conflicts", "dependencies"],
+      "additionalProperties": false
     },
     "info": {
       "type": "object",
@@ -43,8 +44,10 @@
         "description": {"description": "Short description of the AK", "type": "string"},
         "reso": {"description": "Whether this AK intends to introduce a resolution", "type": "boolean"}
       },
-      "required": ["name", "head", "description", "reso"]
+      "required": ["name", "head", "description", "reso"],
+      "additionalProperties": false
     }
   },
-  "required": ["id", "duration", "room_constraints", "time_constraints", "properties", "info"]
+  "required": ["id", "duration", "room_constraints", "time_constraints", "properties", "info"],
+  "additionalProperties": false
 }
diff --git a/schemas/participant.schema.json b/schemas/participant.schema.json
index 1a7d66569b4f7ff23ad88e5db9cd18bc59800472..a7eff8e8f87534d4a50b7789c82a07f6163ebb98 100644
--- a/schemas/participant.schema.json
+++ b/schemas/participant.schema.json
@@ -33,7 +33,8 @@
               ]
             }
           },
-          "required": ["ak_id", "required", "preference_score"]
+          "required": ["ak_id", "required", "preference_score"],
+          "additionalProperties": false
         },
         "uniqueItems": true
     },
@@ -48,8 +49,10 @@
     "info": {
       "type": "object",
       "properties": {"name": {"description": "Name of the person", "type": "string"}},
-      "required": ["name"]
+      "required": ["name"],
+      "additionalProperties": false
     }
   },
-  "required": ["id", "room_constraints", "time_constraints", "info"]
+  "required": ["id", "room_constraints", "time_constraints", "info"],
+  "additionalProperties": false
 }
diff --git a/schemas/room.schema.json b/schemas/room.schema.json
index 80b149e03c4a0fc3fada3c9ceb92d06652dba435..3d921c1c6587d14d6f46542ddd4f35b7fb2427dd 100644
--- a/schemas/room.schema.json
+++ b/schemas/room.schema.json
@@ -26,8 +26,10 @@
       "properties": {
         "name": {"description": "Name of the room", "type": "string"}
       },
-      "required": ["name"]
+      "required": ["name"],
+      "additionalProperties": false
     }
   },
-  "required": ["id", "capacity", "fulfilled_room_constraints", "time_constraints", "info"]
+  "required": ["id", "capacity", "fulfilled_room_constraints", "time_constraints", "info"],
+  "additionalProperties": false
 }
\ No newline at end of file
diff --git a/schemas/solver-output.json b/schemas/solver-output.json
index 20f09176fb5ba77ed5260c20eb1a6e1e3c698dee..15ee65389046f6d5599df5a99d21977a5b6fd487 100644
--- a/schemas/solver-output.json
+++ b/schemas/solver-output.json
@@ -41,7 +41,8 @@
             "uniqueItems": true
           }
         },
-        "required": ["ak_id", "room_id", "timeslot_ids", "participant_ids"] 
+        "required": ["ak_id", "room_id", "timeslot_ids", "participant_ids"],
+        "additionalProperties": false
       },
       "uniqueItems": true
     }
diff --git a/schemas/timeslot.schema.json b/schemas/timeslot.schema.json
index a77d8d0885185c2ff6431f82a67cec10be1d3368..0240c4969741e5d5934938c7000566ef64889f13 100644
--- a/schemas/timeslot.schema.json
+++ b/schemas/timeslot.schema.json
@@ -4,6 +4,7 @@
   "title": "Timeslot",
   "type": "object",
   "required": ["info", "blocks"],
+  "additionalProperties": false,
   "properties": {
     "info": {
       "type": "object",
@@ -19,7 +20,8 @@
           }
         }
       },
-      "required": ["duration"]
+      "required": ["duration"],
+      "additionalProperties": false
     },
     "blocks": {
       "type": "array",
@@ -41,14 +43,16 @@
                 "start": {"description": "Start datetime of the timeslot", "type": "string"},
                 "end": {"description": "End datetime of the timeslot", "type": "string"}
               },
-              "required": ["start", "end"]
+              "required": ["start", "end"],
+              "additionalProperties": false
             },
             "fulfilled_time_constraints": {
               "$ref": "/schema/common/constraints.schema.json",
               "description": "Time constraints fulfilled by this timeslot"
             }
           },
-          "required": ["id", "info", "fulfilled_time_constraints"]
+          "required": ["id", "info", "fulfilled_time_constraints"],
+          "additionalProperties": false
         }
       }
     }