Question 1

How does the image format detector work?

Accepted Answer

The detector reads the first 16 bytes of your file (called the 'magic number' or 'file signature') and matches them against a database of known image format signatures. This works regardless of the file extension, so a PNG renamed to .jpg will still be correctly identified.

Question 2

What image formats are supported?

Accepted Answer

JPEG, PNG, WebP, GIF, BMP, TIFF, HEIC/HEIF, AVIF, ICO, CUR, SVG, PSD, AI, INDD, EPS, JP2, JXL, PBM, PGM, PPM, PNM, XBM, XPM and most other common formats.

Question 3

Does the tool upload my image anywhere?

Accepted Answer

No. The detector runs entirely in your browser using the FileReader API. Your image is never sent to any server — only the first few bytes are read and analyzed locally.

Question 4

Can it tell the difference between WebP, AVIF and HEIC?

Accepted Answer

Yes. WebP, AVIF and HEIC all use the RIFF/ISOBMFF container formats but have distinct magic numbers (RIFF, ftyp avif, ftyp heic). The detector identifies all three and shows the exact format, MIME type and compression type.