It’s all very well if your boss, colleague or printer asks for an ‘InDesign file’. But what should you send them if they’re using a different version of the software?

Use this guide to navigate the murky waters of InDesign file formats, and wise-up on the difference between INDD and IDML, and the right way to down-save or up-save your files.

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1. The Dual Nature of InDesign File Formats

When you create and save a file in Adobe InDesign, you’ll notice that the file has been given the extension .indd. INDD is the extension given to all InDesign files created in the standard way in any version of the design software, whether that’s InDesign CS3, CS4, CS5, CS6 or CC.

If you navigate to an InDesign file in your Finder (Mac OS) or Windows Explorer, you’ll also notice that the InDesign file has been classified in an additional way, under Kind. This indicates which version of InDesign the file was created in; in this case we can see that the file has been created in InDesign CC 2015.

indesign file format indd idml cc can't open indesign file

It is this Kind categorisation that prevents you from opening a CC file in say CS5 or CS6. If you try to open it up, an error message will flag up, informing you that the file is not of a supported file type and cannot be opened in an older version of InDesign.

2. How to Open your Files in any Software Version

Adobe wants to encourage all InDesign users to gravitate to CC, the newest subscription-based version of the software. But this may not be the right choice for everybody—some designers are loyal to older versions of InDesign because of their familiarity with the programme, others might be discouraged by the cost of a subscription-based service.

And guess what? That’s absolutely fine, because you can open any InDesign file in any other version of InDesign if you save the file in the right way.

indesign file format indd idml cc can't open indesign file

If you want to be able to open a file created in an older version of InDesign in a newer version you should have few problems with opening INDD files just as they are. But to down-save (open a file in an older version to the original) or up-save if you’re having problems opening the original file you need to save your work as an IDML file (or INX file for opening in CS3, see below).

An IDML (InDesign Markup) file is a ‘legacy’ file format. Saving your InDesign file as an IDML file allows users of different versions of InDesign to open up the file without a problem.

Saving a CC or CS6 file for opening in CS4, CS5 or CS5.5:

To save your INDD InDesign file as an IDML file, open up the file in InDesign, and go to File > Save As. Select InDesign CS4 or later (IDML) from the drop-down Format menu, and click Save.

indesign file format indd idml cc can't open indesign file

You now have an IDML version of your original InDesign file.

indesign file format indd idml cc can't open indesign file

Saving a CS5 or CS5.5 file for opening in CS4:

With your INDD file opened up, go to File > Export. Choose IDML from the drop-down Format menu and click Save.

Saving a CS5, CS5.5 CS6 or CC file for opening in CS3:

Unfortunately you can’t save back directly from CS5 for opening in CS3. To do this you will have to down-save to CS4 first.

With the INDD file open in CS5 or later choose File > Export. Choose IDML from the Format drop-down menu and hit Save.

Open the IDML file in InDesign CS4. From here, go to File > Export and this time choose InDesign Interchange (INX) as the file Type (Windows) or Format (Mac OS). Click Save to create your INX file, which is now suitable for opening in InDesign CS3.

IMPORTANT: To share your work with others, you should be sure to send a copy of your original INDD file along with the IDML file. The IDML file is linked to the original INDD file; and the IDML file acts as a sort of key which is able to unlock the INDD file.

The best way to share your compatible files with others is to first Package your InDesign file, and then save the IDML file into the packaged folder.

To send the file over email or large file transfer, simply compress the packaged folder (containing both the INDD and IDML files) and attach.

To learn more about using InDesign and develop your design skills pay a visit to our beginner InDesign tutorials page.