diff --git a/cors.go b/cors.go
new file mode 100644
index 0000000..4603fda
--- /dev/null
+++ b/cors.go
@@ -0,0 +1,19 @@
+package main
+
+import (
+	"github.com/gin-gonic/gin"
+)
+
+func corsMiddleware() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		// delete existing headers
+		c.Writer.Header().Del("Access-Control-Allow-Origin")
+		c.Writer.Header().Del("Access-Control-Allow-Methods")
+		c.Writer.Header().Del("Access-Control-Allow-Headers")
+
+		// set new headers
+		c.Writer.Header().Set("Access-Control-Allow-Origin", "*")
+		c.Writer.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE, PATCH")
+		c.Writer.Header().Set("Access-Control-Allow-Headers", "Origin, Authorization, Content-Type")
+	}
+}
diff --git a/main.go b/main.go
index 4a470ae..19f713f 100644
--- a/main.go
+++ b/main.go
@@ -85,12 +85,11 @@ func main() {
 		})
 	})
 
+	// CORS middleware
+	engine.Use(corsMiddleware())
+
 	// CORS handler
 	engine.OPTIONS("/v1/*any", func(ctx *gin.Context) {
-		header := ctx.Writer.Header()
-		header.Set("Access-Control-Allow-Origin", "*")
-		header.Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE, PATCH")
-		header.Set("Access-Control-Allow-Headers", "Origin, Authorization, Content-Type")
 		ctx.AbortWithStatus(200)
 	})
 
diff --git a/process.go b/process.go
index 1f8377f..151800b 100644
--- a/process.go
+++ b/process.go
@@ -113,12 +113,6 @@ func processRequest(c *gin.Context, upstream *OPENAI_UPSTREAM, record *Record, s
 			log.Println("upstream return not 200 and should not response", r.StatusCode)
 			return errors.New("upstream return not 200 and should not response")
 		}
-		r.Header.Del("Access-Control-Allow-Origin")
-		r.Header.Del("Access-Control-Allow-Methods")
-		r.Header.Del("Access-Control-Allow-Headers")
-		r.Header.Set("Access-Control-Allow-Origin", "*")
-		r.Header.Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE, PATCH")
-		r.Header.Set("Access-Control-Allow-Headers", "Origin, Authorization, Content-Type")
 
 		if r.StatusCode != 200 {
 			body, err := io.ReadAll(r.Body)