The IDAP file extension is created by Adobe Systems. IDAP files store a subset of an InDesign document edited by others. They allow importing edited content back into InDesign. If your version of InDesign does not support IDAP, update the software. Adobe sometimes adds compatibility with new formats when updating InDesign. An old version may not support IDAP files. Free online tools allow viewing, editing, converting, merging, and comparing IDAP files without installing anything. Click the links to see details. To open an IDAP file, use Adobe InDesign. The file type likely cannot be exported to other formats. If Windows does not recognize the IDAP extension, it cannot open the file by double-clicking. First determine why Windows cannot open it. Check if the file is associated properly with the software. If not, install a program supporting IDAP files. Adobe InDesign can open IDAP files.