Download in IDM is a WebExtension that enables you to open and download a desired item like a movie, mp3, mp4 .. with an IDM (Internet Download Manager) application. In order to operate with this addon you need a native-client patch to connect your browser with native IDM application in your OS. Please read the following to get more info on how to install native-client and operate with this addon.

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This addon is WebExtension and support for new Firefox Quantum 57.

Note: after installing the extension, you need to connect it with native applications (i.e. IDM) on your machine. If you do not have IDM, please head to (https://www.internetdownloadmanager.com/download.html) and install IDM on your machine. Once you have IDM, you need to make the connection between IDM and your browser. In order to make this connection, a separate patch is provided in GitHub. Please download and install this patch from: https://github.com/alexmarcoo/open-in-native-client/releases

Follow the instructions in the above GitHub page to download and install the related patch to your system. After installing, the "Download in IDM" addon, your browser can communicate with IDM on your machine (i.e. Window OS).

Note: before using the addon, please open the option's page and make sure the path to IDM is correct based on your Operating System. For example, the path to IDM in Window 10 is: C:\Program Files (x86)\Internet Download Manager\IDMan.
Next, please follow the below steps to open and download desired links in IDM.

a. right click on a download link and then click on the Download With IDM (from the context-menu).
b. IDM has several input arguments to enhance downloading desired files. The default argument for downloading is: /d. To get more info about other arguments please open the addon options page and read section arguments. Please note that, you need to add parameters comma separated, for example to automatically download a file write: "/d,/n" in the designated area.
c. you can set the IDM path in your machine from the options page.