STDU Viewer is computer software, a compact viewer for many computer file formats: Portable Document Format (PDF), World Wide Fund for Nature (WWF), DjVu, comic book archive (CBR or CBZ), FB2, ePUB, XML Paper Specification (XPS), Text Compression for Reader (TCR), Mobipocket (MOBI), AZW, multi-page TIFF, text file (TXT), PalmDoc (PDB), Windows Metafile (EMF), Windows Metafile (WMF), bitmap (BMP), Graphics Interchange Format (GIF), JPEG-JPG, Portable Network Graphics (PNG), Photoshop Document (PSD), PiCture eXchang (PCX-DCX). It works under Microsoft Windows, and is free for non-commercial use.