File Type Checker
Drop a file and read its magic bytes to find its true type, then compare that against what the extension claims. Nothing leaves your browser.
Drop a file here
or choose one — nothing leaves your browser
- File name
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- Extension
- —
- Detected type
- —
- First bytes
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What this does
Drop a file here and the tool reads its opening bytes — the file’s “magic number” — to work out what it actually is, then checks that against the extension in its name. It’s a quick way to catch a.jpg that is really a PNG, or a renamed file that won’t open.
The file never leaves your device; only its first few bytes are inspected, in your browser.
Common questions
Is my file uploaded?
No. Only the first bytes are read locally to identify the format. The file itself is never sent anywhere.
Which formats can it detect?
Common image, document, audio, video, and archive formats have distinctive signatures and are the most reliable to detect. Plain text formats such as.txt, .csv, or .json have no signature, so they cannot be verified this way.
Why does my .docx show up as a ZIP?
Modern Office files (.docx, .xlsx,.pptx) are really ZIP archives inside, so they share the ZIP signature. The tool treats those extensions as a legitimate match.