@Chrimaeon By the way reason are encode based64 is to reduce size from original size by 50% compression. Without it, some server will reject the big size. Because I try it without encode and compression and directly send file my server will reject for big the size. Secondly, I do not have to set "application", "octet-stream" because I already tested and working fined in my side. Hopefully answer your question in my medium. tq