Free local-processing tool
Image File Signature Checker
Check the image header against the filename extension and report dimensions.
Settings and export
Select an image to start.
Files stay on this device. No login, server image upload or hidden paid API is used.
How to use Image File Signature Checker
- Select a compatible image saved on your device.
- Review the preview and settings. Try a smaller image if your device has limited memory.
- Choose Process locally, inspect the output and download the result.
What this tool does
Spot misleading extensions and inspect common format identifiers without uploading the file.
Useful limitations
A matching header does not prove a file is safe or wholly valid; malware scanning is not provided. Browser decode support and color profiles vary, and local device memory limits apply. For animation, only one still frame is used.
Privacy and compatibility
The selected file is read locally with browser APIs. It is not sent to this website’s server. Outputs are generated locally; some exports become PNG, text/JSON or single-page PDF according to the tool. Keep an unedited original and check the result carefully.
See supported formats, privacy details and the complete tool directory.