Real File Type Detector
The File Type Detector tool scans the first few bytes of any file's actual content and compares them against a database of known binary signatures (magic bytes) for dozens of common formats — PDF, PNG, JPEG, ZIP, MP3, MP4, executables, and more — to determine its real type. It also flags when the filename's extension doesn't match the detected type, a common sign of a malicious executable renamed with an image or document extension to trick a user. All scanning happens in your browser; the file is never uploaded to a server.
The file's bytes are inspected directly inside your browser; the file is never uploaded to any server.
Drag a file here or choose one
Any file type
What this tool does
Identifies a file's real type from its contents rather than its extension, reporting the MIME type and expected extensions, and whether the extension matches what the content says.
When to use it
- A file with no extension that you cannot identify.
- Checking whether a file you received really is what its extension claims.
- A file that will not open despite having a plausible extension.
- Inspecting a file before opening it, out of caution.
How to use it
- Put the file on the drop area or choose it.
- Wait for detection to finish.
- Read the detected type, the MIME type and the expected extensions, and whether the result is a match or a mismatch.
A practical example
Input
A file named report.pdf whose contents are actually a PNG image.
Output
A detected type of PNG with a mismatch warning, because the extension says PDF and the content says otherwise.
Limitations
- Detection relies on the signature at the start of the file; types without a distinctive signature — plain text, for instance — may come back as unknown.
- A mismatch does not necessarily mean a file is malicious; it may simply have been renamed for an innocent reason.
- A match does not guarantee the file is safe or free of harmful content.
Privacy and processing
The file is examined on your device and is never uploaded — which means you can inspect a suspicious file without sending it to anyone.
Technical notes
- Detection reads only the file's first bytes, so it is immediate even for large files.
Frequently Asked Questions
No — only the first bytes of the file are read and scanned entirely in your browser via JavaScript; the file itself is never uploaded to a server.