Enobil Labs File Extension Detector

Identify unknown file types by matching magic bytes and file signatures locally in your browser

Why Use Our File Extension Detector?

🔒 Complete Local Confidentiality
File bytes are read and matched entirely in browser memory. Nothing is transmitted to a server, so sensitive or private files are safe to inspect.
📚 Nearly 100 Signatures Documented
Covers images, audio, video, archives, documents, executables, fonts, disk images, and databases — with the full supported list published on this page.
🧭 Extension-Independent Detection
Identifies a file by its actual byte content, so a renamed, mislabeled, or extension-less file is still detected correctly.
📴 Offline Operation
Once the page is loaded, the signature database and detection logic run completely offline — no internet connection required.

Frequently Asked Questions

❓ Is my file uploaded to any servers to detect its type?

No. The entire file is read and analyzed locally using the browser's FileReader API. Only the first few kilobytes of the file are ever inspected, and the raw bytes never leave your machine.

❓ How does file type detection work if the extension is missing or wrong?

Most file formats start with a distinctive sequence of bytes known as a "magic number" or file signature, regardless of what the file is named. This tool compares the start of your file against a database of nearly 100 known signatures to identify the true format, independent of the filename or extension.

❓ What file types are supported?

Images (PNG, JPEG, GIF, BMP, WebP, TIFF, HEIC/AVIF, PSD, SVG...), audio (MP3, WAV, FLAC, OGG, MIDI...), video (MP4, MOV, MKV/WebM, AVI, FLV...), archives (ZIP, RAR, 7Z, GZIP, TAR...), documents (PDF, RTF, legacy MS Office...), executables (Windows PE, ELF, Mach-O, WebAssembly...), fonts (TTF, OTF, WOFF/WOFF2), disk images, databases, and more. The full list is documented on this page below the upload panel.

❓ Can it tell DOCX, XLSX, PPTX, EPUB, JAR, and APK apart from a plain ZIP file?

Yes, with a heuristic. Those formats are all ZIP archives internally, so after confirming the ZIP signature, the tool scans the first few kilobytes for characteristic internal paths (like word/, xl/, ppt/, or AndroidManifest.xml) to refine the result. If none of those markers are found, it reports a generic ZIP Archive.

❓ Why does it sometimes show more than one possible match?

A few binary formats share byte-identical magic numbers (for example, Java .class files and Mach-O fat binaries both start with CA FE BA BE). When that happens, the tool lists every equally-specific match rather than guessing, so you can use context (like where the file came from) to decide.