InDesign files are not backwards compatible. To open a 2026 file in CS6 or 2024, you must convert it to
.indd, go to File > Export and choose InDesign Markup (IDML). Send this file to your collaborator. They can open it in their older version..indd file. You must ask the sender to export an IDML file for you.If you are looking for that magic website, here is the hard truth: However, there are "better" ways to handle this problem if you know where to look. online indesign version converter better