Browser-only tool
MIME sniffer and file signature viewer
Select a file to inspect browser MIME type, extension, and first bytes in hex. Useful for debugging uploads and basic content-type sanity checks.
Warning: signature detection is heuristic. It does not prove file safety and does not replace backend validation.
Privacy And Limitations
Files are read locally in your browser and are not uploaded by this static page.
- Signature matching is heuristic and cannot guarantee full file safety or format validity.
- Many formats share overlapping magic bytes, so deeper parsing may be required.
- Do not treat MIME sniffing as malware analysis or legal content verification.
FAQ
Does this upload files?
No. It reads selected bytes locally in the browser.
Is MIME sniffing always accurate?
No. It is a practical hint and should be combined with backend validation.
Can this detect malware?
No. It is not antivirus or malware scanning.
Why inspect magic bytes?
They help detect mismatches between extension, declared MIME type, and probable format.
Should backend still validate files?
Yes. Client-side checks are convenience only and must not replace server-side validation.