Image Format Detector
Detect the true file format of any image by reading its magic bytes, not extension.
- Free to use
- Browser-based processing
- No account required
- Files never uploaded
About Image Format Detector
The Image Format Detector identifies an image's true format by reading its magic bytes — the signature at the start of the file — rather than trusting the file extension. It reveals when a file has been renamed or mislabeled, for example a PNG saved with a .jpg extension. Detection runs in the browser with no upload.
How to Use Image Format Detector
- 1
Upload a file
Add the image file you want to check.
- 2
Detect the format
The tool reads the file's magic bytes to determine its real format.
- 3
See the result
View the true format alongside the file's extension to spot mismatches.
Frequently Asked Questions
What are magic bytes?
Most file formats start with a fixed signature of bytes. Reading them reveals the real format regardless of what the extension says.
Why would a file have the wrong extension?
Files get renamed, exported oddly, or relabeled. A .jpg that's actually a PNG can confuse software that trusts the extension.
Which formats can it detect?
Common image formats including JPG, PNG, GIF, WebP, BMP and more, each with a distinct byte signature.
Is my file uploaded?
No. Detection reads the first bytes in your browser; nothing is sent to a server.