diff --git a/Prototype/server/src/utils/minio.ts b/Prototype/server/src/utils/minio.ts
index ed39987..b9c49b4 100644
--- a/Prototype/server/src/utils/minio.ts
+++ b/Prototype/server/src/utils/minio.ts
@@ -3,11 +3,26 @@ import minioClient from "../storage";
 
 /**
  * Remove slash at the start and ensure slash at the end of the path
+ * @param path - path to be check and ensure
+ * @returns path without / at start and end with trailing slash
  */
 function safePath(path: string) {
   return path.replace(/^\/|\/$/g, "") + "/";
 }
 
+/**
+ * Replace illegal character eg. ? % < > / \ : | that can't be in path with "-".
+ * @param path - string to check and replace
+ * @returns path with illegal character replaced with "-"
+ */
+export function replaceIllegalChars(path: string, replaceChar = "-") {
+  return path.replace(/[/\\?%*:|"<>]/g, "-");
+}
+
+/**
+ * Utility function to check for .keep file if it is exist or not.
+ * @returns true if .keep exist, false otherwise
+ */
 export async function pathExist(path: string): Promise<boolean> {
   return await minioClient
     .statObject("ehr", `${safePath(path)}.keep`)
@@ -18,6 +33,11 @@ export async function pathExist(path: string): Promise<boolean> {
     });
 }
 
+/**
+ * Utility function to list folder by using .keep file with prefix in minio.
+ * @param path - path to list
+ * @return list of folder with metadata
+ */
 export function listFolder(path?: string): Promise<EhrFolder[]> {
   if (path) path = safePath(path);