Check a suspicious file
filename = invoice.pdf.exe
Result: ⚠️ Double extension detected — high risk. This is a common malware trick.
File Extension Analyzer
Evaluate a filename's extension for security risks, expected MIME types, and trustworthiness. Identifies high-risk extensions (like .exe, .bat), medium-risk extensions (like .scr, .jar), and safe types (like .pdf, .png). Warns when an extension is commonly used for malware delivery.
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
Verify a safe file
filename = photo.jpg
Result: ✅ Low risk — expected MIME: image/jpeg.
Frequently asked questions
Can a file be dangerous even with a safe extension?
Yes! Extensions can be forged. A .jpg file could actually be an executable. Always use the MIME Type Detector (magic bytes) to verify the true file type.
What is a double extension attack?
Malware authors sometimes use double extensions like "invoice.pdf.exe" to trick users into thinking the file is a PDF when it is actually an executable.
What should I do with high-risk extensions?
Only open high-risk files from trusted sources. Scan them with antivirus software first. If in doubt, use the MIME Type Detector to verify the actual file type.
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