File type identifier — read the magic bytes
Find a file's true type from its content, not its extension. It reads entirely in your browser (0 uploads, works offline).
How to use it
- Choose any file.
- Read the detected type, MIME and extension.
- Copy or Download the result.
FAQ
How do I identify a file's real type for free?
Choose the file and this page reads its first bytes — the magic-number signature — to name the true format, on your device with no upload. The file itself never leaves your browser.
Why not just trust the extension?
Extensions can be wrong or misleading; a .jpg might actually be a PNG or something else. The magic bytes reveal what the file really is.
Is my file uploaded anywhere?
No. Only the first few bytes are read, entirely in your browser, and nothing is transmitted or stored, which you can verify by turning off your Wi-Fi.
Which formats does it recognise?
Common ones — PNG, JPEG, GIF, WebP, PDF, ZIP/Office, RAR, GZIP, MP3, MP4, ELF and plain text — with a text fallback for printable content.
Limits
Recognises common signatures; unusual or container formats may report the container (e.g. ZIP for Office files).
Related
The hex viewer shows the raw bytes; the file checksum verifier checks integrity.
Bookmark this page (Ctrl+D, or ⌘D on Mac) or install the app — it works offline the next time you need it.