File Type Checker
Find out what a file really is, even if the extension is missing or wrong.
Runs in your browser. Nothing is uploaded Free, no sign-up Works on mobile
Choose files to inspect
Only the first 4 KB of each file is read
How to use File Type Checker
- Choose one or more files.
- See the real type detected from the content.
- Watch for warnings where the extension doesn’t match.
Frequently asked questions
How does it know the real type?
Most formats start with a unique signature (“magic bytes”), such as %PDF for PDFs or PK for ZIP-based files like DOCX.
Why is a DOCX shown as ZIP?
DOCX, XLSX and PPTX files are ZIP archives internally, so that is expected.
Are my files uploaded?
No. Files are read and processed by your browser on your own device, so there is no upload wait and no size limit set by a server.
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