To help your work flow smoothly and efficiently, most file types are accepted on the Upwork platform. This includes .doc, .docx, .pdf, .txt, .ppt, .gif, and .png. The supported file types are the same everywhere attachments are available (proposals, job posts, projects, messages, etc.).
Unsupported file types
.ade, .adp, .bat, .chm, .cmd, .com, .cpl, .exe, .hta, .ins, .isp, .jar, .jse, .lib, .lnk, .mde, .msc, .msp, .mst, .pif, .scr, .sct, .shb, .sys, .vb, .vbe, .bs, .vxd, .wsc, .wsf, .wsh
The .zip file type is not currently supported for iOS devices.