diff --git a/customHeaders.go b/customHeaders.go
new file mode 100644
index 0000000..0056021
--- /dev/null
+++ b/customHeaders.go
@@ -0,0 +1,100 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// HeaderConfigArray is the array which contains all the custom header rules
+type HeaderConfigArray struct {
+	Configs []HeaderConfig `json:"configs"`
+}
+
+// HeaderConfig is a single header rule specification
+type HeaderConfig struct {
+	Path          string            `json:"path"`
+	FileExtension string            `json:"fileExtension"`
+	Headers       []HeaderDefiniton `json:"headers"`
+}
+
+// HeaderDefiniton is a key value pair of a specified header rule
+type HeaderDefiniton struct {
+	Key   string `json:"key"`
+	Value string `json:"value"`
+}
+
+var headerConfigs HeaderConfigArray
+
+func fileExists(filename string) bool {
+	info, err := os.Stat(filename)
+	if os.IsNotExist(err) {
+		return false
+	}
+	return !info.IsDir()
+}
+
+func initHeaderConfig() bool {
+	headerConfigValid := false
+
+	if fileExists("/config/headerConfig.json") {
+		jsonFile, err := os.Open("/config/headerConfig.json")
+		if err != nil {
+			fmt.Println("Cant't read header config file. Error:")
+			fmt.Println(err)
+		} else {
+			byteValue, _ := ioutil.ReadAll(jsonFile)
+
+			json.Unmarshal(byteValue, &headerConfigs)
+
+			if len(headerConfigs.Configs) > 0 {
+				headerConfigValid = true
+				fmt.Println("Found header config file. Rules:")
+
+				for i := 0; i < len(headerConfigs.Configs); i++ {
+					configEntry := headerConfigs.Configs[i]
+					fmt.Println("==============================================================")
+					fmt.Println("Path: " + configEntry.Path)
+					fmt.Println("FileExtension: " + configEntry.FileExtension)
+					for j := 0; j < len(configEntry.Headers); j++ {
+						headerRule := configEntry.Headers[j]
+						fmt.Println(headerRule.Key, ":", headerRule.Value)
+					}
+					fmt.Println("==============================================================")
+				}
+			} else {
+				fmt.Println("No rules found in header config file.")
+			}
+
+		}
+		jsonFile.Close()
+	}
+
+	return headerConfigValid
+}
+
+func customHeadersMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		reqFileExtension := filepath.Ext(r.URL.Path)
+
+		for i := 0; i < len(headerConfigs.Configs); i++ {
+			configEntry := headerConfigs.Configs[i]
+
+			fileMatch := configEntry.FileExtension == "*" || reqFileExtension == "."+configEntry.FileExtension
+			pathMatch := configEntry.Path == "*" || strings.HasPrefix(r.URL.Path, configEntry.Path)
+
+			if fileMatch && pathMatch {
+				for j := 0; j < len(configEntry.Headers); j++ {
+					headerEntry := configEntry.Headers[j]
+					w.Header().Set(headerEntry.Key, headerEntry.Value)
+				}
+			}
+		}
+
+		next.ServeHTTP(w, r)
+	})
+}
diff --git a/main.go b/main.go
index 40480b9..b2617e6 100644
--- a/main.go
+++ b/main.go
@@ -14,9 +14,6 @@ import (
 	"strconv"
 	"strings"
 	"sync"
-	"encoding/json"
-	"os"
-	"path/filepath"
 )
 
 var (
@@ -70,15 +67,8 @@ func (w *gzipResponseWriter) Write(b []byte) (int, error) {
 	return w.Writer.Write(b)
 }
 
-func handleReq(h http.Handler, headerConfigs HeaderConfigs) http.Handler {
+func handleReq(h http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		/*
-		log.Println("======================")
-		log.Println("path =>", r.URL.Path)
-		log.Println("extension =>", filepath.Ext(r.URL.Path))
-		log.Println("pagedata =>", strings.HasPrefix(r.URL.Path, "/page-data"))
-		log.Println("======================")
-		*/
 		if *httpsPromote && r.Header.Get("X-Forwarded-Proto") == "http" {
 			http.Redirect(w, r, "https://"+r.Host+r.RequestURI, http.StatusMovedPermanently)
 			if *logRequest {
@@ -91,91 +81,14 @@ func handleReq(h http.Handler, headerConfigs HeaderConfigs) http.Handler {
 			log.Println(r.Method, r.URL.Path)
 		}
 
-		// apply custom header config
-		if (len(headerConfigs.Configs) > 0) {
-			reqFileExtension := filepath.Ext(r.URL.Path)
-
-			for i := 0; i < len(headerConfigs.Configs); i++ {
-				configEntry := headerConfigs.Configs[i]
-
-				fileMatch := configEntry.FileExtension == "*" || reqFileExtension == "."+ configEntry.FileExtension
-				pathMatch := configEntry.Path == "*" || strings.HasPrefix(r.URL.Path, configEntry.Path)
-
-				// log.Println("fileMatch", reqFileExtension, configEntry.FileExtension)
-				// log.Println("pathMatch", r.URL.Path, configEntry.Path)
-
-				if fileMatch && pathMatch {
-					log.Println(r.URL.Path, configEntry.FileExtension, configEntry.Path)
-					for j := 0; j < len(configEntry.Headers); j++ {
-						headerEntry := configEntry.Headers[j]
-
-						log.Println("add header", headerEntry.Key, headerEntry.Value, "to", r.URL.Path)
-						w.Header().Set(headerEntry.Key, headerEntry.Value)
-					}
-				}
-			}
-		}
-
 		h.ServeHTTP(w, r)
 	})
 }
 
-type HeaderConfigs struct {
-	Configs []HConfig `json:"configs"`
-}
-
-type HConfig struct {
-	Path string `json:"path"`
-	FileExtension string `json:"fileExtension"`
-	Headers []Header `json:"headers"`
-}
-
-type Header struct {
-	Key string `json:"key"`
-	Value string `json:"value"`
-}
-
-
-func initHeaderConfig() HeaderConfigs {
-	if fileExists("/config/headerConfig.json") {
-		jsonFile, err := os.Open("/config/headerConfig.json")
-		if err != nil {
-			fmt.Println(err)
-		}
-
-		byteValue, _ := ioutil.ReadAll(jsonFile)
-
-		var headerConfigs HeaderConfigs
-
-		json.Unmarshal(byteValue, &headerConfigs)
-
-		fmt.Println("Found header config file. Rules:")
-
-		for i := 0; i < len(headerConfigs.Configs); i++ {
-			fmt.Println("==============================================================")
-			fmt.Println("Path: " + headerConfigs.Configs[i].Path)
-			fmt.Println("FileExtension: " + headerConfigs.Configs[i].FileExtension)
-			for j := 0; j < len(headerConfigs.Configs); j++ {
-				headerRule := headerConfigs.Configs[i].Headers[j]
-				fmt.Println(headerRule.Key, ":", headerRule.Value)
-			}
-			fmt.Println("==============================================================")
-		}
-
-		jsonFile.Close()
-
-		return headerConfigs
-	} else {
-		return nil
-	}
-}
-
 func main() {
 
 	flag.Parse()
 
-	headerConfigs := initHeaderConfig()
-
 	// sanity check
 	if len(*setBasicAuth) != 0 && !*basicAuth {
 		*basicAuth = true
@@ -192,7 +105,7 @@ func main() {
 		}
 	}
 
-	handler := handleReq(http.FileServer(fileSystem), headerConfigs)
+	handler := handleReq(http.FileServer(fileSystem))
 
 	pathPrefix := "/"
 	if len(*context) > 0 {
@@ -210,6 +123,11 @@ func main() {
 		handler = authMiddleware(handler)
 	}
 
+	headerConfigValid := initHeaderConfig()
+	if headerConfigValid {
+		handler = customHeadersMiddleware(handler)
+	}
+
 	// Extra headers.
 	if len(*headerFlag) > 0 {
 		header, headerValue := parseHeaderFlag(*headerFlag)