Exchangeable image file format (EXIF) is a metadata format used by digital cameras to embed some useful information regarding the image files being saved. Since this is metadata and is embedded inside the image files (for example inside the JPEG images), ordinary image viewers are not able to display it readily. Some image viewer software actually need special plugins to display this EXIF information.
The same is true for the web browsers – they can display all the images but fail to display any metadata inside those images. If you want to see the EXIF data embedded inside any of the online images through your Firefox web browser then you can install the FxIF extension.
After the installation of the FxIF extension, you can simply right-click on any image that is displayed in the Firefox web browser and choose View Image Details from the right-click menu. This will display a small window where the EXIF data of that image is displayed in a tabular format.
However, there are many images that do not contain the EXIF data at all. For those images it will simply inform you that no metadata is found. When it does display the EXIF data for any of the images, you can use the option to save the EXIF data in the JSON format to a local file on your hard drive. You can also copy the same data to the clipboard and use it in any text editor.
FxIF does not allow you to edit or remove the data from the images. If you want to add, edit or remove the EXIF metadata then perhaps you will find the QuickImageComment software of use. It can be used to edit not only EXIF but IPTC and XMP metadata too.
You can download FxIF extension for Firefox from https://addons.mozilla.org/en-US/firefox/addon/viewexif/.