Image Format Detector
Detect the true format of any image by reading its file signature (magic bytes). All processing happens in your browser — your files never leave your device.
Drag & Drop Your Image Here
or
Supports JPEG, PNG, GIF, WebP, BMP, SVG, ICO, TIFF and more
How to Use
- Click "Select Image" or drag and drop any image file into the workspace above.
- The tool reads the file's magic bytes (binary signature) to detect its true format, regardless of the file extension.
- Review the detailed analysis including true format, MIME type, file size, dimensions, color depth, and transparency support.
- Click "Analyze Another Image" to check a different file.
Frequently Asked Questions
What are magic bytes?
Magic bytes (also called file signatures) are specific byte sequences at the beginning of a file that identify its true format. For example, JPEG files always start with FF D8 FF, and PNG files start with 89 50 4E 47. This tool reads these bytes to determine the actual format, even if the file extension has been changed or is incorrect.
Why does the detected format differ from the file extension?
File extensions can be easily renamed or may be wrong. For instance, someone might rename a PNG to .jpg, or a file downloaded from the web may have a generic extension. The magic bytes reveal the true format because they are embedded in the file data itself and cannot change without altering the file content.
What image formats can this tool detect?
This tool can detect JPEG, PNG, GIF (both GIF87a and GIF89a), WebP, BMP, SVG, ICO, and TIFF (both little-endian and big-endian). It reads the binary file signature to make an accurate identification regardless of the file extension.
Are my files uploaded to a server?
No. All analysis happens entirely in your browser using the JavaScript FileReader API. Your images are never sent to any server and never leave your device. The tool processes everything locally for complete privacy.
How is transparency detected?
The tool draws the image onto an HTML5 Canvas and samples pixel data to check for alpha channel values below 255 (fully opaque). Formats like PNG, WebP, and GIF support transparency, while JPEG and BMP typically do not.