Identify Unknown File
Find out what an old or unknown file is and how to open it
Drop any file - even one with no extension
Single File • Max 500MB
How it works
- We read the first bytes of the file and compare them with 98 known legacy formats.
- The extension is used only as a tie-breaker, so renamed or extension-less files still work.
- You get the format, its creator, its era, and a link to the converter that opens it.
Only the file header is inspected. Nothing is stored: the upload is discarded as soon as the report is produced.
Formats we recognise
98 formats. Extensions in grey are aliases of the same format.
| Extension | Format | Converts to |
|---|---|---|
| .wpd.wp .wp5 .wp6 .wpt | WordPerfect DocumentReveal-codes formatting is mapped to styles; fonts are substituted. | pdfdocxodtrtftxthtml |
| .wps | Microsoft Works Word ProcessorWorks 3-9 supported. Embedded clip art may be dropped. | pdfdocxodtrtftxthtml |
| .wri | Windows Write DocumentWindows 3.x Write files. | pdfdocxodtrtftxthtml |
| .lwp | Lotus Word Pro DocumentLotus SmartSuite word processor. | pdfdocxodtrtftxthtml |
| .sam | Ami Pro DocumentAmi Pro 2-3 text format. | pdfdocxodtrtftxthtml |
| .sxw.sdw .stw | StarOffice / OpenOffice.org 1.x WriterPredecessor of ODT. | pdfdocxodtrtftxthtml |
| .cwk.cws | ClarisWorks / AppleWorks DocumentWord-processing, drawing and spreadsheet documents are supported. | pdfdocxodtrtftxthtml |
| .mcw.mw .mwii | MacWrite / MacWrite II DocumentClassic Mac OS word processor. | pdfdocxodtrtftxthtml |
| .hwp | Hangul Word Processor DocumentHWP 3.x and 5.x are supported. | pdfdocxodtrtftxthtml |
| .abw.zabw | AbiWord DocumentXML-based; converts cleanly. | pdfdocxodtrtftxthtml |
| .doc | Word 6/95/97-2003 or Word for DOS DocumentVery old Word for DOS (1-5) and Word 2.0 for Windows files are also recognised. | pdfdocxodtrtftxthtml |
| .pages | Apple Pages DocumentPages '05-'09 and newer bundles (zipped) are supported. | pdfdocxodtrtftxthtml |
| .602 | T602 DocumentCzech DOS-era word processor. | pdfdocxodtrtftxthtml |
| .rtf | Rich Text FormatStill readable, but old RTF 1.x quirks are handled. | pdfdocxodttxthtml |
| .wk1.wks .wk2 | Lotus 1-2-3 Worksheet (Release 2)Formulas are recalculated on import; macros are dropped. | xlsxpdfodscsv |
| .wk3.wk4 | Lotus 1-2-3 Worksheet (Release 3/4)Multi-sheet workbooks are preserved. | xlsxpdfodscsv |
| .123 | Lotus 1-2-3 Workbook (97/Millennium) | xlsxpdfodscsv |
| .wq1.wq2 .wb1 .wb2 .wb3 .qpw | Quattro Pro for DOS Spreadsheet | xlsxpdfodscsv |
| .xlw.xls | Excel 4/5 Workbook | xlsxpdfodscsv |
| .sxc.sdc .stc | StarOffice / OpenOffice.org 1.x Calc | xlsxpdfodscsv |
| .dbf | dBASE Database TableOpens as a single sheet; memo (.dbt) fields are not included. | xlsxpdfodscsv |
| .numbers | Apple Numbers Spreadsheet | xlsxpdfodscsv |
| .dif | Data Interchange Format | xlsxpdfodscsv |
| .slk.sylk | SYLK Spreadsheet | xlsxpdfodscsv |
| .sxi.sdd .sti | StarOffice / OpenOffice.org 1.x Impress | pdfpptxodp |
| .key | Apple Keynote PresentationKeynote 1-5 and newer bundles are supported; transitions are dropped. | pdfpptxodp |
| .ppt | PowerPoint 4/95/97-2003 Presentation | pdfpptxodp |
| .shw | Corel Presentations Show | pdfpptxodp |
| .pub | Microsoft Publisher DocumentPublisher 98-2016 layouts open as drawings; text remains selectable in PDF. | pdfpngsvg |
| .cdr.cmx | CorelDRAW DrawingCorelDRAW 7-X7 supported. Effects like lenses may render simplified. | pdfpngsvg |
| .vsd.vss .vst .vdx | Microsoft Visio Drawing | pdfpngsvg |
| .pmd.pm6 .p65 | Adobe PageMaker PublicationPageMaker 6-7. Linked images must be embedded to appear. | pdfpngsvg |
| .qxp.qxd | QuarkXPress DocumentQuarkXPress 3.1-4.1 supported. | pdfpngsvg |
| .fh.fh8 .fh9 .fh10 .fh11 | Macromedia FreeHand DrawingFreeHand 8-11 (MX). | pdfpngsvg |
| .zmf | Zoner Draw / Callisto Drawing | pdfpngsvg |
| .wpg | WordPerfect Graphics | pdfpngsvg |
| .sda.sxd .std | StarOffice / OpenOffice.org 1.x Draw | pdfpngsvg |
| .emf.wmf | Windows Enhanced Metafile | pdfpngsvg |
| .pcx | ZSoft PC Paintbrush Image | pngjpgwebptiffpdf |
| .tga.targa .icb .vda .vst | Truevision Targa ImageNo header magic; identified by extension or footer. | pngjpgwebptiffpdf |
| .xcf | GIMP ImageLayers are flattened. | pngjpgwebptiffpdf |
| .psd.pdd | Adobe Photoshop DocumentUses the embedded composite image; layers are flattened. | pngjpgwebptiffpdf |
| .pict.pct .pic | Apple QuickDraw PictureClassic Mac OS clipboard/graphics format. | pngjpgwebptiffpdf |
| .ras.sun | Sun Raster Image | pngjpgwebptiffpdf |
| .sgi.rgb .rgba .bw .iris | SGI / IRIS RGB Image | pngjpgwebptiffpdf |
| .xpm | X PixMap Image | pngjpgwebptiffpdf |
| .xbm | X BitMap Image | pngjpgwebptiffpdf |
| .dds | DirectDraw Surface TextureGame texture format; mipmaps are discarded. | pngjpgwebptiffpdf |
| .iff.ilbm .lbm | Amiga IFF / ILBM Image | pngjpgwebptiffpdf |
| .mac.pntg | MacPaint Image | pngjpgwebptiffpdf |
| .msp | Microsoft Paint (Windows 1/2) Image | pngjpgwebptiffpdf |
| .cut | Dr. Halo Image | pngjpgwebptiffpdf |
| .wbmp | Wireless Bitmap | pngjpgwebptiffpdf |
| .jp2.j2k .jpx | JPEG 2000 Image | pngjpgwebptiffpdf |
| .fpx | Kodak FlashPix ImageReads the highest-resolution layer. | pngjpgwebptiffpdf |
| .pcd | Kodak Photo CD ImageExtracts the 768x512 base image. | pngjpgwebptiffpdf |
| .eps.ps .ai | Encapsulated PostScriptRasterised via Ghostscript when converting to PNG/JPG. | pdfpngjpg |
| .djvu.djv | DjVu Scanned DocumentMulti-page bundles are converted to a single PDF. | pdf |
| .mdi | Microsoft Document ImagingNo open-source decoder exists. Open in Office 2007 MODI or Windows XP Mode and print to PDF. | Identify only |
| .rm.rmvb .rv | RealMedia VideoRealVideo 3/4 (RV30/RV40) decode fully; RV10/20 may be lower quality. | mp4webmmovmp3 |
| .wmv.asf | Windows Media VideoDRM-protected files cannot be converted. | mp4webmmovmp3 |
| .flv.f4v | Flash Video | mp4webmmovmp3 |
| .swf | Shockwave Flash MovieOnly embedded video/frames are extracted; interactive content is lost. | mp4webmgif |
| .3gp.3g2 .3gpp | 3GPP Mobile VideoFeature-phone video. | mp4webmmovmp3 |
| .vob.mpg .mpeg .dat | DVD Video ObjectMultiple audio/subtitle tracks: first track is kept. | mp4webmmovmp3 |
| .mod.tod | JVC / Panasonic Camcorder VideoMPEG-2 from tapeless camcorders. | mp4webmmovmp3 |
| .dv | Digital Video (DV) StreamRaw DV from MiniDV camcorders. | mp4webmmovmp3 |
| .avi | Audio Video Interleave (legacy codecs)Cinepak, Indeo, DivX 3 and other 90s codecs are decoded. | mp4webmmovmp3 |
| .mov.qt | QuickTime Movie (legacy codecs)Sorenson, Cinepak and Apple Video codecs are decoded. | mp4webmmovmp3 |
| .divx | DivX Video | mp4webmmovmp3 |
| .ogm | Ogg Media Video | mp4webmmovmp3 |
| .nsv | Nullsoft Streaming Video | mp4webmmovmp3 |
| .ra.ram | RealAudio | mp3wavflacoggm4a |
| .wma | Windows Media AudioDRM-protected files cannot be converted. | mp3wavflacoggm4a |
| .au.snd | Sun / NeXT Audio | mp3wavflacoggm4a |
| .aiff.aif .aifc | Audio Interchange File Format | mp3wavflacoggm4a |
| .voc | Creative Voice File | mp3wavflacoggm4a |
| .amr | Adaptive Multi-Rate AudioVoice recordings from feature phones. | mp3wavflacoggm4a |
| .mid.midi | MIDI SequenceMIDI holds notes, not audio; render it with a soundfont in a DAW or MuseScore. | Identify only |
| .mod.xm .s3m .it | Amiga / ProTracker ModuleRendered with libopenmpt. | mp3wavflacoggm4a |
| .ape | Monkey's Audio | mp3wavflacoggm4a |
| .mpc | Musepack Audio | mp3wavflacoggm4a |
| .dss | Digital Speech Standard (dictation) | mp3wavflacoggm4a |
| .shn | Shorten Lossless Audio | mp3wavflacoggm4a |
| .arj | ARJ Archive | Extract files |
| .lzh.lha | LHA / LZH Archive | Extract files |
| .arc | ARC Archive | Extract files |
| .zoo | ZOO Archive | Extract files |
| .sit.sitx | StuffIt ArchiveStuffIt 1.5-5 and StuffIt X (.sitx) are supported. | Extract files |
| .ace | ACE Archive | Extract files |
| .cab | Microsoft Cabinet Archive | Extract files |
| .z | Unix compress Archive | Extract files |
| .cpt | Compact Pro Archive | Extract files |
| .hqx | BinHex Encoded File | Extract files |
| .dms | Amiga DiskMasher Image | Extract files |
| .rar | RAR Archive (old versions)RAR 1.5-5 supported. | Extract files |
| .chm | Compiled HTML HelpExtracted as the original HTML pages and images. | Extract files |
| .iso.img .bin | Disc ImageFiles are extracted from the image. | Extract files |
What is the Unknown File Identifier?
A file with a strange extension, or none at all, is the most common dead end when going through an old computer or backup disk. Windows says it 'cannot open this file type', web searches for the extension return generic listings, and guessing programs to try wastes an afternoon. This tool answers the real question in seconds: what is this file, which program made it, roughly when, and what can I turn it into today? It works from the file's actual byte signature, the same technique digital archivists use, so it is not fooled by wrong or missing extensions.
Key Features & Benefits
Signature-based detection
Reads magic bytes at known offsets, including deep offsets like the ISO 9660 descriptor and ProTracker module tags.
Container awareness
Recognises OLE, ZIP and RIFF containers and explains what may be inside when the exact format is ambiguous.
libmagic second opinion
A low-level description from the same database used by the Unix 'file' command is shown alongside our own result.
Straight to the fix
Every identified format links to the exact converter or extractor that handles it, with the right target pre-selected.
How to Use the the Unknown File Identifier
Drop the mystery file
Any file, any size up to 500MB. The extension does not matter and may be missing entirely.
Read the report
See the detected format, the software that produced it, its era, known conversion limitations and the detection confidence.
Open it
Click the suggested converter. It is pre-set to the detected format so you can convert immediately.
Not convertible?
For formats without an open-source decoder we tell you exactly which legacy software or workaround to use.
Practical Use Cases
Files from floppy disks
DOS-era files were often saved with cryptic 8.3 names and no meaningful extension.
Renamed attachments
Email systems and old CMS exports frequently strip or rewrite extensions.
Backup dumps
Recovery tools produce thousands of files named by number. Identify what is worth keeping.
Digital archiving
Catalogue a collection by real format rather than by trusting file names.
FAQs
Does the file extension matter?
No. Detection is based on the bytes inside the file. The extension is only used to break ties when several formats share the same container (for example Publisher, Visio and Works all use Microsoft's OLE container).
What does the confidence score mean?
0.98 means the byte signature and extension agree; 0.85 means the signature matched but the extension is missing or different; 0.6 means we only recognised the extension because that format has no reliable signature (for example TGA images).
What if nothing matches?
You still get the container type and a libmagic description, which usually narrows it down to a family such as 'MS Windows executable' or 'data'. Truly unknown binary data is reported honestly as unknown.
Is my file uploaded and stored?
It is uploaded so the server can read it, but nothing is written to disk and the report contains only metadata.