The file extension INDL identifies library, ie library files of the DTP (Desktop Publishing) solution InDesign. With InDesign, for example, you can create print templates and layouts for print products such as flyers, catalogs or brochures.
Using library files, you can systematically organize common graphics, text, and pages, as well as add and manage guides, grids, drawn shapes, and grouped images.
Libraries can be easily created by highlighting the desired objects and the subsequent menu choice 'File-> New-> Library'. Alternatively, you can select 'New' in the Library panel or drag the highlighted one into the Library panel. The menu 'File-> open' can theoretically open any number of libraries. These can then be accessed via the Library panel.
It should be noted that library files have the extension INDL only under Windows, they apparently have no extension on the Apple Mac. Library files of older InDesign versions are automatically converted to the new format when loaded.
Most often resolving problems with opening INDL files is very simple. Just install an appropriate program that supports such files. All of the listed programs support INDL files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of INDL files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate INDL files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the Adobe InDesign applications is not on the list, select "Browse" option in order to manually locate the directory where Adobe InDesign has been installed.
Sometimes problems with opening INDL files may not lie with the application itself, but can arise due to other causes, such as: