Image Format Detector

Free Online Image Format Detector

Every image file begins with a short sequence of bytes called a "magic number" or file signature, which identifies the format regardless of what the file is named. A file called photo.jpg might actually be a PNG inside, or a download might be missing its extension entirely. LovePDFImg's Image Format Detector reads these signature bytes and tells you the file's real format, and flags whether it matches the extension and declared MIME type.

This is useful for troubleshooting upload errors, verifying files before processing them in other tools, or simply confirming what format a mystery file actually is. The tool reads only the first handful of bytes from your file using the browser's File API — nothing is uploaded, and the rest of the file is never even read.

How to Detect an Image's Real Format

1. 1Upload your fileDrag and drop any file, or click to browse — image or otherwise.
2. 2View the detected formatThe tool reads the file's signature bytes and shows the actual format.
3. 3Compare with the extension and MIME typeSee whether the file's name and declared type match its real content.

Frequently Asked Questions