diff --git a/heatmap-tool/backend/main.py b/heatmap-tool/backend/main.py
index 2b42ff49..ffc08d76 100644
--- a/heatmap-tool/backend/main.py
+++ b/heatmap-tool/backend/main.py
@@ -44,6 +44,7 @@ def read_root():
 @app.post("/api/upload")
 async def upload_file(file: UploadFile = File(...)):
     global df_storage, plz_column_name
+    print(f"--- Received request to /api/upload for file: {file.filename} ---")
     if not file.filename.endswith('.xlsx'):
         raise HTTPException(status_code=400, detail="Invalid file format. Please upload an .xlsx file.")
 
@@ -77,16 +78,20 @@ async def upload_file(file: UploadFile = File(...)):
 
         df_storage = df
         
+        print(f"Successfully processed file. Found PLZ column: '{plz_column_name}'. Detected {len(filters)} filterable columns.")
         return {"filename": file.filename, "filters": filters, "plz_column": plz_column_name}
 
     except Exception as e:
+        print(f"ERROR processing file: {e}")
         raise HTTPException(status_code=500, detail=f"An error occurred while processing the file: {e}")
 
 
 @app.post("/api/heatmap")
 async def get_heatmap_data(request: FilterRequest):
     global df_storage, plz_column_name
+    print(f"--- Received request to /api/heatmap with filters: {request.filters} ---")
     if df_storage is None:
+        print("ERROR: No data in df_storage. File must be uploaded first.")
         raise HTTPException(status_code=404, detail="No data available. Please upload a file first.")
 
     try:
@@ -117,7 +122,9 @@ async def get_heatmap_data(request: FilterRequest):
                     "count": row["count"]
                 })
         
+        print(f"Generated heatmap data with {len(heatmap_data)} PLZ points.")
         return heatmap_data
 
     except Exception as e:
+        print(f"ERROR generating heatmap: {e}")
         raise HTTPException(status_code=500, detail=f"An error occurred while generating heatmap data: {e}")
diff --git a/heatmap-tool/frontend/src/App.tsx b/heatmap-tool/frontend/src/App.tsx
index f81e1530..45b3258d 100644
--- a/heatmap-tool/frontend/src/App.tsx
+++ b/heatmap-tool/frontend/src/App.tsx
@@ -36,7 +36,7 @@ function App() {
     setIsLoading(true);
     setError(null);
     try {
-      const response = await axios.post('http://backend:8000/api/heatmap', {
+      const response = await axios.post('/api/heatmap', {
         filters: selectedFilters,
       });
       setHeatmapData(response.data);
diff --git a/heatmap-tool/frontend/src/components/FileUpload.tsx b/heatmap-tool/frontend/src/components/FileUpload.tsx
index 9afa667a..a50e39ef 100644
--- a/heatmap-tool/frontend/src/components/FileUpload.tsx
+++ b/heatmap-tool/frontend/src/components/FileUpload.tsx
@@ -39,7 +39,7 @@ const FileUpload: React.FC<FileUploadProps> = ({ onUploadSuccess, setIsLoading,
     setError(null);
 
     try {
-      const response = await axios.post('http://backend:8000/api/upload', formData, {
+      const response = await axios.post('/api/upload', formData, {
         headers: {
           'Content-Type': 'multipart/form-data',
         },
diff --git a/heatmap-tool/frontend/vite.config.ts b/heatmap-tool/frontend/vite.config.ts
index 8b0f57b9..7fba83a1 100644
--- a/heatmap-tool/frontend/vite.config.ts
+++ b/heatmap-tool/frontend/vite.config.ts
@@ -4,4 +4,13 @@ import react from '@vitejs/plugin-react'
 // https://vite.dev/config/
 export default defineConfig({
   plugins: [react()],
+  server: {
+    proxy: {
+      '/api': {
+        target: 'http://backend:8000',
+        changeOrigin: true,
+        rewrite: (path) => path.replace(/^\/api/, ''),
+      },
+    }
+  }
 })