diff --git a/.idea/runConfigurations/vue01.xml b/.idea/runConfigurations/vue01.xml
index 69b67ab..d0116f3 100644
--- a/.idea/runConfigurations/vue01.xml
+++ b/.idea/runConfigurations/vue01.xml
@@ -1,5 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="vue01" type="Python.FastAPI">
+    <option name="additionalOptions" value="--reload --host 0.0.0.0 --port 4433" />
     <option name="file" value="$PROJECT_DIR$/backend/main.py" />
     <module name="vue01" />
     <option name="ENV_FILES" value="" />
diff --git a/backend/main.py b/backend/main.py
index 6d7c6d9..a313ce2 100644
--- a/backend/main.py
+++ b/backend/main.py
@@ -1,6 +1,27 @@
-from fastapi import FastAPI
+from contextlib import asynccontextmanager
 
-app = FastAPI()
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from backend.src import router
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    yield
+
+
+app = FastAPI(lifespan=lifespan)
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+app.include_router(router.calendar)
 
 
 @app.get("/")
diff --git a/backend/src/__init__.py b/backend/src/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/backend/src/router/__init__.py b/backend/src/router/__init__.py
new file mode 100644
index 0000000..6b9152f
--- /dev/null
+++ b/backend/src/router/__init__.py
@@ -0,0 +1 @@
+from .calendar import calendar
\ No newline at end of file
diff --git a/backend/src/router/calendar.py b/backend/src/router/calendar.py
new file mode 100644
index 0000000..6dd819b
--- /dev/null
+++ b/backend/src/router/calendar.py
@@ -0,0 +1,41 @@
+import datetime
+
+from dateutil.relativedelta import relativedelta
+from fastapi import APIRouter, HTTPException
+
+calendar = APIRouter(
+    prefix="/calendar",
+    tags=["calendar"],
+)
+
+
+@calendar.get("/", response_model=list[datetime.date])
+async def get_calendar(
+        year: int = None,
+        month: int = None,
+):
+    """Get a list of weekday dates for a month.
+
+    By default, the current month is used.
+
+    If **year** is provided, **month** must be provided, too.
+    """
+    if year is not None:
+        if month is None:
+            raise HTTPException(status_code=422,
+                                detail=[
+                                    dict(type="missing parameter",
+                                         loc=["query", "month"],
+                                         msg="month must be provided when year is provided")])
+    else:
+        today = datetime.date.today()
+        month = today.month
+        year = today.year
+    date = datetime.date(year, month, 1)
+    end_date = date + relativedelta(day=31)
+    result = []
+    while date <= end_date:
+        if date.isoweekday() < 6:
+            result.append(date)
+        date += relativedelta(days=1)
+    return result
diff --git a/backend/test_main.http b/backend/test_main.http
index a2d81a9..b60c510 100644
--- a/backend/test_main.http
+++ b/backend/test_main.http
@@ -1,11 +1,11 @@
 # Test your FastAPI endpoints
 
-GET http://127.0.0.1:8000/
+GET http://127.0.0.1:4433/
 Accept: application/json
 
 ###
 
-GET http://127.0.0.1:8000/hello/User
+GET http://127.0.0.1:4433/hello/User
 Accept: application/json
 
 ###
diff --git a/pyproject.toml b/pyproject.toml
index 12d57e5..21b159a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -5,5 +5,6 @@ description = "Add your description here"
 requires-python = ">=3.13"
 dependencies = [
     "fastapi>=0.116.1",
+    "python-dateutil>=2.9.0.post0",
     "uvicorn>=0.35.0",
 ]