Universal Viewer Technical Specifications

Previewing is available for various file formats in the Synology Drive web portal.
Universal Viewer is compatible with DSM 7.0 or above.
General file-format preview support can vary by operating system and device.

Images: .3fr, .arw, .bmp, .cr2, .crw, .dcr, .dng, .erf, .gif, .ico, .jfif, .jpe, .jpeg, .jpg, .k25, .kdc, .mef, .mos, .mrw, .nef, .orf, .pef, .png, .ptx, .raf, .raw, .rw2, .sr2, .srf, .svg, .tif, .tiff, .x3f, .webp
- Smooth previews and thumbnail generation are available for raw images.
Text: .diff, .erl, .json, .lst, markdown, .md, .mdown, .mkdn, .out, .patch, .sml, .txt
Compressed files: .7z, .bz2, .gz, .jar, .lzh, .rar, .rpm, .tar, .tbz, .tgz, .txz, .xz, .zip, .zipx
Office: .osheet, .oslides, .odoc, .xlsx, .pptx, .docx, .ods, .odt, .odp, .csv
Code: actproj, .ad, .akp, .applescript, .as, .asax, .asc, .ascx, .asm, .asmx, .asp, .aspx, .asr, .as3, .bat, .bkpi, .c, .cc, .cmake, .coffee, .cpp, .cs, .css, .cxx, .erb, .groovy, .gvy, .h, .haml, .hh, .hpp, .hxx, .java, .js, .jsx, .less, .m, .make, .mhtml, .ml, .mm, .php, .pl, .plist, .properties, .py, .rb, .sass, .scala, .scm, .script, .scss, .sh, .sql, .swift, .tsx, .vb, .vi, .vim, .xhtml, .xml, .xsd, .xsl, .yaml, .yml
Others: .pdf, .psd, .htm, .html

Video: Preview support is limited to formats compatible with the browser and operating system; transcoding is not supported. Learn more
Audio: Preview support is limited to formats compatible with the browser and operating system; transcoding is not supported. Learn more

Starting from DSM 7.2.2, Universal Viewer no longer generates HEIC/HEIF thumbnails and previews on Synology storage systems through Advanced Media Extensions (AME).
The HEIC/HEIF change reduces server-side load and unnecessary resource usage because most end devices now support the HEVC (H.265) codec. Learn more about workarounds