PrivTab

Image Format Detector

Check what format an image file really is, even if its extension says something else.

Runs in your browser · No uploads

Drag & drop images here

or

Any image file, one or many. Only the start of each file is read.

Your files stay on your device. Nothing is uploaded.

You can also paste an image or screenshot with Ctrl+V (⌘V on a Mac).

  • Nothing leaves your device
  • No server-imposed size limits
  • No sign-up, no watermark
  • Free

How to check an image format

  1. Choose one or more images.
  2. Read the real format, MIME type, dimensions and details for each file.
  3. If the extension is wrong, rename the file or convert it with the Image Converter.

Why the extension can be wrong

A file name is only a label. Images are often saved with the wrong extension, for example a WebP downloaded as .jpg, or an iPhone HEIC photo renamed to .jpg. Some apps then refuse to open them. This tool reads the first bytes of the file, where every format stores its own signature, so the result does not depend on the name.

Formats it recognizes

JPEG, PNG and animated PNG, GIF, WebP, AVIF, HEIC and HEIF, BMP, ICO, TIFF, SVG, JPEG XL, JPEG 2000, Photoshop PSD and common camera RAW formats.

Is my image uploaded?

No. Your image is processed locally in your browser and never leaves your device. This site has no upload feature, and its security policy blocks the page from uploading anything.

Frequently asked questions

How can I tell if a JPG is really a JPG?

Choose the file. The detector shows the real format from the file contents and warns you when it does not match the extension.

Does it read the whole file?

Only the beginning is needed to identify the format. Dimensions are read from the image when your browser can open that format.

Are my images uploaded?

No. Detection runs in your browser.