IconJar is a macOS desktop app for organizing icons, which is very helpful if you work with lots of icons. It helps to search, recolor, resize, export and drop the icons into any software of your choice. It works great for bulk edits and exports.
Downloading icons in Iconjar format is a feature supported for Pro Unlimited users.
You can download Free icon sets in Iconjar format too, without being a subscriber. If you are looking for Premium icons, you need Pro Unlimited.
How it works
To download a set in IconJar format, simply click the arrow on the green Download all icons button at the top right corner on a set preview page and choose Download as IconJar file.
When you download the IconJar format from Iconfinder it will appear in your Downloads folder as a .zip file. When you extract the .zip, double clicking the IconJar file will open the icons directly in IconJar app, where they will be automatically organised and described.
Read more about What icon format is suitable for your intended use.