diff --git a/backend/api/helpers/check_folder_structure.py b/backend/api/helpers/check_folder_structure.py
index b1bf70a0..bfac3e4b 100644
--- a/backend/api/helpers/check_folder_structure.py
+++ b/backend/api/helpers/check_folder_structure.py
@@ -152,6 +152,8 @@ def check_zip_structure(
         folder_structure,
         zip_file_path,
         restrict_extra_folders=False):
+    # print(f"Checking folder_structure: {folder_structure}")
+    # print(f"Checking zip_file_path: {zip_file_path}")
     """
     Check the structure of a zip file.
 
diff --git a/backend/api/models/project.py b/backend/api/models/project.py
index 839907a1..0cecf456 100644
--- a/backend/api/models/project.py
+++ b/backend/api/models/project.py
@@ -1,8 +1,10 @@
 from django.db import models
+from datetime import timedelta
 from django.utils import timezone
 from api.models.course import Course
 
 
+# TODO max submission size
 class Project(models.Model):
     """Model that represents a project."""
 
@@ -61,6 +63,14 @@ def deadline_passed(self):
         now = timezone.now()
         return now > self.deadline
 
+    def is_archived(self):
+        """Returns True if a project is archived."""
+        return self.archived
+
+    def is_visible(self):
+        """Returns True if a project is visible."""
+        return self.visible
+
     def toggle_visible(self):
         """Toggles the visibility of the project."""
         self.visible = not self.visible
@@ -70,3 +80,7 @@ def toggle_archived(self):
         """Toggles the archived status of the project."""
         self.archived = not self.archived
         self.save()
+
+    def increase_deadline(self, days):
+        self.deadline = self.deadline + timedelta(days=days)
+        self.save()
diff --git a/backend/api/models/submission.py b/backend/api/models/submission.py
index 531f07a0..174f5265 100644
--- a/backend/api/models/submission.py
+++ b/backend/api/models/submission.py
@@ -18,7 +18,7 @@ class Submission(models.Model):
     )
 
     # Multiple submissions can be made by a group
-    submission_number = models.PositiveIntegerField(blank=False, null=False)
+    submission_number = models.PositiveIntegerField(blank=True, null=True)
 
     # Automatically set the submission time to the current time
     submission_time = models.DateTimeField(auto_now_add=True)
@@ -49,7 +49,6 @@ class SubmissionFile(models.Model):
         null=False,
     )
 
-    # TODO - Set the right place to save the file
     file = models.FileField(blank=False, null=False)
 
 
diff --git a/backend/api/serializers/group_serializer.py b/backend/api/serializers/group_serializer.py
index 92847e7f..35a61402 100644
--- a/backend/api/serializers/group_serializer.py
+++ b/backend/api/serializers/group_serializer.py
@@ -16,9 +16,14 @@ class GroupSerializer(serializers.ModelSerializer):
         read_only=True,
     )
 
+    submissions = serializers.HyperlinkedIdentityField(
+        view_name="group-submissions",
+        read_only=True,
+    )
+
     class Meta:
         model = Group
-        fields = ["id", "project", "students", "score"]
+        fields = ["id", "project", "students", "score", "submissions"]
 
     def validate(self, data):
         # Make sure the score of the group is lower or equal to the maximum score
diff --git a/backend/api/serializers/project_serializer.py b/backend/api/serializers/project_serializer.py
index a906177c..e05397e2 100644
--- a/backend/api/serializers/project_serializer.py
+++ b/backend/api/serializers/project_serializer.py
@@ -1,5 +1,10 @@
+from django.utils.translation import gettext
 from rest_framework import serializers
-from ..models.project import Project
+from api.models.project import Project
+from api.models.group import Group
+from rest_framework.exceptions import ValidationError
+from api.models.submission import Submission, SubmissionFile
+from api.serializers.submission_serializer import SubmissionSerializer
 
 
 class ProjectSerializer(serializers.ModelSerializer):
@@ -43,3 +48,21 @@ class Meta:
 
 class TeacherCreateGroupSerializer(serializers.Serializer):
     number_groups = serializers.IntegerField(min_value=1)
+
+
+class SubmissionAddSerializer(SubmissionSerializer):
+    def validate(self, data):
+        group: Group = self.context["group"]
+        project: Project = group.project
+
+        # Check if the project's deadline is not passed.
+        if project.deadline_passed():
+            raise ValidationError(gettext("project.error.submission.past_project"))
+
+        if not project.is_visible():
+            raise ValidationError(gettext("project.error.submission.non_visible_project"))
+
+        if project.is_archived():
+            raise ValidationError(gettext("project.error.submission.archived_project"))
+
+        return data
diff --git a/backend/api/serializers/submission_serializer.py b/backend/api/serializers/submission_serializer.py
index 744cd4ac..d75cd853 100644
--- a/backend/api/serializers/submission_serializer.py
+++ b/backend/api/serializers/submission_serializer.py
@@ -1,5 +1,7 @@
 from rest_framework import serializers
 from ..models.submission import Submission, SubmissionFile, ExtraChecksResult
+from api.helpers.check_folder_structure import check_zip_file  # , parse_zip_file
+from django.db.models import Max
 
 
 class SubmissionFileSerializer(serializers.ModelSerializer):
@@ -45,3 +47,44 @@ class Meta:
             "structure_checks_passed",
             "extra_checks_results"
         ]
+        extra_kwargs = {
+            "submission_number": {
+                "required": False,
+                "default": 0,
+            }
+        }
+
+    def create(self, validated_data):
+        # Extract files from the request
+        request = self.context.get('request')
+        files_data = request.FILES.getlist('files')
+
+        # Get the group for the submission
+        group = validated_data['group']
+
+        # Get the project associated with the group
+        project = group.project
+
+        # Get the maximum submission number for the group's project
+        max_submission_number = Submission.objects.filter(
+            group__project=project
+        ).aggregate(Max('submission_number'))['submission_number__max'] or 0
+
+        # Set the new submission number to the maximum value plus 1
+        validated_data['submission_number'] = max_submission_number + 1
+
+        # Create the Submission instance without the files
+        submission = Submission.objects.create(**validated_data)
+
+        pas: bool = True
+        # Create SubmissionFile instances for each file and check if none fail structure checks
+        for file in files_data:
+            SubmissionFile.objects.create(submission=submission, file=file)
+            status, _ = check_zip_file(submission.group.project, file.name)
+            if not status:
+                pas = False
+
+        # Set structure_checks_passed to True
+        submission.structure_checks_passed = pas
+        submission.save()
+        return submission
diff --git a/backend/api/views/admin_view.py b/backend/api/views/admin_view.py
index 63fdab43..ad0862d0 100644
--- a/backend/api/views/admin_view.py
+++ b/backend/api/views/admin_view.py
@@ -3,6 +3,6 @@
 from authentication.models import User
 
 
-class AdminViewSet(viewsets.ModelViewSet):
+class AdminViewSet(viewsets.ReadOnlyModelViewSet):
     queryset = User.objects.filter(is_staff=True)
     serializer_class = UserSerializer
diff --git a/backend/api/views/group_view.py b/backend/api/views/group_view.py
index 7c86b3db..632bb7ff 100644
--- a/backend/api/views/group_view.py
+++ b/backend/api/views/group_view.py
@@ -10,6 +10,9 @@
 from api.serializers.group_serializer import GroupSerializer
 from api.serializers.student_serializer import StudentSerializer
 from api.serializers.group_serializer import StudentJoinGroupSerializer, StudentLeaveGroupSerializer
+from api.serializers.project_serializer import SubmissionAddSerializer
+from api.serializers.submission_serializer import SubmissionSerializer
+from rest_framework.request import Request
 
 
 class GroupViewSet(CreateModelMixin,
@@ -36,6 +39,20 @@ def students(self, request, **_):
         )
         return Response(serializer.data)
 
+    @action(detail=True, permission_classes=[IsAdminUser])
+    def submissions(self, request, **_):
+        """Returns a list of students for the given group"""
+        # This automatically fetches the group from the URL.
+        # It automatically gives back a 404 HTTP response in case of not found.
+        group = self.get_object()
+        submissions = group.submissions.all()
+
+        # Serialize the student objects
+        serializer = SubmissionSerializer(
+            submissions, many=True, context={"request": request}
+        )
+        return Response(serializer.data)
+
     @students.mapping.post
     @students.mapping.put
     def _add_student(self, request, **_):
@@ -74,3 +91,22 @@ def _remove_student(self, request, **_):
         return Response({
             "message": gettext("group.success.student.remove"),
         })
+
+    @submissions.mapping.post
+    @submissions.mapping.put
+    def _add_submission(self, request: Request, **_):
+        """Add an submission to the group"""
+
+        group: Group = self.get_object()
+
+        # Add submission to course
+        serializer = SubmissionAddSerializer(
+            data=request.data, context={"group": group, "request": request}
+        )
+
+        if serializer.is_valid(raise_exception=True):
+            serializer.save(group=group)
+
+        return Response({
+            "message": gettext("group.success.submissions.add")
+        })
diff --git a/backend/api/views/project_view.py b/backend/api/views/project_view.py
index 761496f1..4365b78c 100644
--- a/backend/api/views/project_view.py
+++ b/backend/api/views/project_view.py
@@ -10,6 +10,7 @@
 from ..serializers.checks_serializer import StructureCheckSerializer, ExtraCheckSerializer
 from api.serializers.project_serializer import ProjectSerializer, TeacherCreateGroupSerializer
 from api.serializers.group_serializer import GroupSerializer
+from api.serializers.submission_serializer import SubmissionSerializer
 
 
 class ProjectViewSet(CreateModelMixin,
@@ -22,7 +23,7 @@ class ProjectViewSet(CreateModelMixin,
     serializer_class = ProjectSerializer
     permission_classes = [IsAdminUser | ProjectPermission]  # GroupPermission has exact the same logic as for a project
 
-    @action(detail=True, methods=["get"], permission_classes=[IsAdminUser | ProjectGroupPermission])
+    @action(detail=True, permission_classes=[IsAdminUser | ProjectGroupPermission])
     def groups(self, request, **_):
         """Returns a list of groups for the given project"""
         # This automatically fetches the group from the URL.
@@ -37,6 +38,23 @@ def groups(self, request, **_):
 
         return Response(serializer.data)
 
+    """
+    @action(detail=True, permission_classes=[IsAdminUser])
+    def submissions(self, request, **_):
+        # Returns a list of subbmisions for the given project
+        # This automatically fetches the group from the URL.
+        # It automatically gives back a 404 HTTP response in case of not found.
+        project = self.get_object()
+        submissions = project.submissions.all()
+
+        # Serialize the group objects
+        serializer = SubmissionSerializer(
+            submissions, many=True, context={"request": request}
+        )
+
+        return Response(serializer.data)
+    """
+
     @groups.mapping.post
     def _create_groups(self, request, **_):
         """Create a number of groups for the project"""
diff --git a/data/production/structures/empty.zip b/data/production/structures/empty.zip
new file mode 100644
index 00000000..15cb0ecb
Binary files /dev/null and b/data/production/structures/empty.zip differ