diff --git a/projects/services.py b/projects/services.py
new file mode 100644
index 0000000..50b9a64
--- /dev/null
+++ b/projects/services.py
@@ -0,0 +1,40 @@
+from .models import Project
+
+
+ACTION_FIELD_MAP = {
+            'like': 'likers',
+            'scrap': 'scrappers',
+        }
+
+class ProjectBeforeRelCheckService:
+    @staticmethod
+    def check_user_project_rel(action_type: str, project: Project, user):
+        action = ACTION_FIELD_MAP.get(action_type)
+        if not action:
+            raise ValueError(f"'{action_type}' is unsupported action type")
+
+        if getattr(project, action).filter(id=user.id).exists():
+            return True
+        else:
+            return False
+
+class ProjectStateChangeService:
+    @staticmethod
+    def change_user_project_rel(action_type: str, project: Project, user, add=True):
+        action = ACTION_FIELD_MAP.get(action_type)
+        if not action:
+            raise ValueError(f"'{action_type}' is unsupported action type")
+
+        user_method = getattr(getattr(project, action), 'add' if add else 'remove')
+        user_method(user)
+
+    @staticmethod
+    def change_count_project_state(action_type: str, project: Project, add=True):
+        action = ACTION_FIELD_MAP.get(action_type)
+        if not action:
+            raise ValueError(f"'{action_type}' is unsupported action type")
+        field_name = action_type + '_count'
+        current_count = getattr(project, field_name)
+        now_count = current_count+1 if add else max(current_count-1, 0)
+        setattr(project, field_name, now_count)
+        project.save(update_fields=[field_name])