An API file is a so-called Adobe Ink Colors Setup file, that is, an ink-color setting file of the Photoshop image-editing software. An API file contains data for the correct settings when printing images on an inkjet printer. In this way, colors matched or calibrated to a particular output device (printer) are applied to an image.
Most often resolving problems with opening API files is very simple. Just install an appropriate program that supports such files. All of the listed programs support API files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of API 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 API 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 Acrobat applications is not on the list, select "Browse" option in order to manually locate the directory where Adobe Acrobat has been installed.
Sometimes problems with opening API files may not lie with the application itself, but can arise due to other causes, such as: