File Info
See everything your browser knows about a file: exact size, MIME type, extension and last-modified date — plus the true file type detected from its binary signature. Free and 100% private: your files never leave your device.
or click to browse — documents, images, archives, media, executables · stays on your device
How to use the File Info tool
- Pick a file. Drag and drop any file into the box above, or click it to browse. You can select several files at once — each gets its own report.
- Read the details. The report shows the file name, exact size in bytes, extension, the MIME type your browser reports, the last-modified timestamp and a hex preview of the first bytes.
- Verify the true type. The tool reads the file's binary signature (magic number) and tells you what the content really is — with a warning if it doesn't match the extension. Copy the report with one click.
About this tool
This free online file information viewer inspects the metadata of any file without installing software. It recognises the binary signatures of dozens of common formats — PNG, JPEG, GIF, WebP, PDF, ZIP, RAR, 7z, GZIP, TAR, MP3, MP4, MKV, WAV, OGG, FLAC, TIFF, PSD, SQLite, fonts, Windows and Linux executables, Office documents and more. Because it checks the actual content instead of trusting the file name, it can unmask renamed files: a "photo.jpg" that is really an executable, or a mystery download with no extension at all.
Everything happens locally in your browser: the tool reads only the first few kilobytes of the file to identify the signature, and nothing is ever uploaded, stored or logged. That makes it safe for confidential documents and a handy first step before opening an email attachment you don't fully trust.
Frequently asked questions
What is a file signature or "magic number"?
Most file formats start with a fixed sequence of bytes that identifies the format — for example every PNG image begins with the bytes 89 50 4E 47 and every PDF starts with %PDF. This tool reads those first bytes and matches them against a database of known signatures, which is far more reliable than trusting the file extension.
Why does the detected type not match the file extension?
The file was probably renamed at some point, or the program that created it used the wrong extension. The extension is just part of the file name — changing "song.mp3" to "song.pdf" doesn't change the content. When the tool shows a mismatch warning, the detected signature reflects what the file really contains.
Is my file uploaded to a server?
No. The file is analysed entirely in your browser using the JavaScript File API. Only the first few kilobytes are read for signature detection, and no data leaves your device — you can even use the tool offline once the page is loaded.
Why is the MIME type empty or generic?
Browsers guess the MIME type from the file extension using the operating system's registry. If the extension is unknown or missing, the browser reports an empty type or a generic one like application/octet-stream. The signature-based "Detected type" row is the more trustworthy answer in those cases.