File Opener — Detect, View & Extract Any File
Drop any file. We detect the type by magic numbers and show you exactly what it is and how to use it. Browser-only, no upload, 100% private.
What This Tool Does (and What AI Cannot)
Reads the first 16 bytes (magic numbers) to identify the true type. AI models can only guess from filenames - they cannot parse binary headers.
Lists & extracts contents from ZIP / APK / JAR / EPUB / CRX archives directly in your browser using fflate.
Reads DOCX files and renders the text content. PDF, images, audio, video all preview inline.
For files we cannot open, we tell you what the file is, what opens it, and route you to the right tool on DevTools Hub.
All processing happens in your browser using WebAssembly and JavaScript. Zero uploads, zero tracking.
APK, RAR, ZIP, DLL, DAT, BIN, CRDOWNLOAD, TMP, DOC, DOCX, PDF, JPG, PNG, MP4, MP3, ISO, DEB, RPM, IPA, EXE, MSI, DMG, CLASS, SWF, MDB, ACCDB, OD...
Why does my file show as "Unknown"?
If the first 16 bytes don't match any known signature, the file is either: (1) a custom/proprietary format, (2) a renamed file, (3) a corrupted or truncated file, or (4) a format we haven't added yet. The tool will still show the first 256 bytes as a hex preview so you can manually verify the file.
Is my file uploaded anywhere?
No. This tool runs entirely client-side. Your file is read with the FileReader API and never sent to any server. You can verify this by checking the Network tab in DevTools - zero outbound requests are made for the file content.
Can AI open APK, RAR, DLL, DAT, BIN files?
No. AI language models (ChatGPT, Claude, Gemini) cannot parse real binary file formats. They can only guess from filenames. Our tool uses real magic number detection (the same technique as the Unix file command) to identify what the file actually is, and we can extract & preview the contents of supported formats.
How do I open a .crdownload file?
A .crdownload file is a Chrome partial download. The extension is just Chrome's way of locking the file while downloading. Once the download completes, Chrome renames it to its final name. If the download was interrupted, the file is incomplete and the partial download is still inside. You cannot open a .crdownload directly - re-download the file in Chrome.
How do I open a .dll file?
A .dll (Dynamic Link Library) is a Windows shared library. You don't "open" it - the operating system loads it when an application needs its code. To view its functions, use a tool like Dependency Walker or dumpbin on Windows. To see the metadata, open it in a hex editor.
How do I open a .dat file?
.dat is a generic extension used by many programs. A winmail.dat file is from Outlook and contains attachments - use our detection to see if it's that format. Otherwise, try opening it with Notepad or the program that created it.