If someone sends you a 2024 file and you only have 2021, you cannot open it. Since you cannot export to IDML yourself, you need a service to do it for you.
This is the official and most reliable way to "downsave" a file. IDML files are universal and can be opened by any version from CS4 to the present. Steps (requires the newer version of InDesign): Open the file in the version of InDesign. File > Export From the "Format" dropdown, select InDesign Markup (IDML) Open this .idml file in the how to convert indesign file to older version free
If you own InDesign CS6 or older, and the file was made in CC 2024, you cannot magically convert the file without some access to a newer machine. Here are two free alternatives: If someone sends you a 2024 file and
Do not use "Save As." Use Export .
The good news: You don’t need sketchy online converters or paid software. Here is the step-by-step guide. IDML files are universal and can be opened
If you do not have access to a newer version of InDesign to perform the export, you can use these free tools and methods:
: In your current version of InDesign, go to File > Export .