Verify a file's actual type
file = (rename a .jpg to .txt and test)
Result: Shows the real MIME type from magic bytes, flagging any extension mismatch.
File MIME Type Detector
Identify a file's actual type by reading its magic bytes (file signature). File extensions can be changed or forged, but the binary signature at the start of the file reveals the true format. Detects images, documents, archives, executables, audio/video, and more. All processing happens in your browser.
Privacy: this tool processes your data entirely in your browser. Nothing you paste or type is sent to the server.
Enter your values and press Calculate — the result appears here.
Worked examples
Frequently asked questions
Why not just use the file extension?
File extensions can be changed, renamed, or forged. Malware often disguises itself by using innocent-looking extensions like .jpg or .txt. Magic bytes are part of the file's binary content and are much harder to fake.
What are magic bytes?
Magic bytes (also called file signatures) are specific byte sequences at the beginning of a file that identify its format. For example, PNG files always start with 0x89 0x50 0x4E 0x47.
Is my file uploaded?
No. Only the first 300 bytes are read in your browser. The file never leaves your device.
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