IDML vs INDD: Which InDesign File Should You Send?
A translation agency sends you a file. Or you're preparing one to send. Either way, someone needs to choose: INDD or IDML? And the wrong answer breaks the workflow before the first word is translated.
Clients often send the wrong format, translators are not always told what the format changes, and many DTP handoffs start with an email asking for the file to be exported again. This article explains which format to send, and when.
What is an INDD file?
INDD is InDesign's native working format. It stores everything the software uses to render the layout: text frames, links to images, colour swatches, parent pages, layers, paragraph styles, object states and interactive elements. It is binary, not human-readable, and tied to the InDesign version that saved it.
An INDD file saved in InDesign 2025 cannot be opened directly in InDesign 2022. The reliable way back to an older version is IDML. If you send an INDD and the DTP provider is on an older version, they may not be able to open it.
INDD is the file you work in day to day, built for production work in InDesign.
What is an IDML file?
IDML stands for InDesign Markup Language. It is an open, XML-based exchange format that Adobe introduced in CS4 to solve the version problem. An IDML file is a ZIP archive of XML files: one per spread, one per story, plus files for styles, fonts and preferences. You can rename it to .zip and unzip it to see the raw structure.
Because IDML is XML, CAT tools like Trados Studio, memoQ, and Phrase can parse it directly: they extract the text from the stories for translation and write it back into the same structure.
IDML opens across versions. A file exported from InDesign 2025 as IDML opens in older versions back to CS4; features the older version does not have are dropped or simplified.
INDD vs IDML side by side
| Property | INDD | IDML |
|---|---|---|
| Format type | Binary, proprietary | XML-based, open |
| Version compatibility | Same version or newer only | Opens in any version from CS4 |
| Works in CAT tools (Trados, memoQ) | Not supported natively | Fully supported |
| File size | Larger (caches resources) | Smaller (structure only) |
| Fonts embedded | No | No (referenced by name) |
| Images embedded | Usually linked | Usually linked |
| Human-readable | No | Yes (XML) |
| Preserves all InDesign features | Yes (fully) | Mostly; some newer features may differ |
| Sent with links and fonts | Yes, via File › Package | Only inside a package (Include IDML); a bare IDML has neither |
| Ideal for active design work | Yes | Can be opened and edited |
| Ideal for translation handoff | No | Yes |
Which format should you send?
The right answer depends on who receives the file and what they do with it:
Translator / CAT tool
The translator is working in Trados, memoQ, Phrase, or Wordfast. Send IDML, the InDesign format these tools are built for; they cannot open INDD.
DTP provider on different InDesign version
If you are on InDesign 2025 and they are on 2022, the INDD will not open. IDML will. Export IDML whenever the provider's version is unknown.
DTP provider doing layout work
If the DTP provider is doing full layout work, not just a text swap, send an InDesign package: INDD, all linked images and the fonts. A bare IDML is not enough for production.
Archive or backup across teams
IDML is a safe archive format: it opens in later and earlier InDesign versions, independent of the version that created it.
Translation agency managing the full project
Some agencies translate in-tool, others hand off to DTP separately. Ask which workflow they use before choosing the format.
Client doesn't have InDesign
The client needs to review structure or text content without InDesign. IDML is more likely to be parseable by third-party tools than INDD.
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The standard translation workflow with IDML
Working file
File › Export › IDML
Translation
Fix overset, adjust
Final deliverable
The IDML is the handoff format between the designer and the translator. After translation, the DTP provider receives the translated IDML back from the CAT tool, opens it in InDesign and does the layout work (overset text, frames, text expansion) before exporting the final PDF.
Fonts and linked images are never embedded in IDML. The file references them by path and name. If the DTP provider does not have the fonts, or the image links are broken, the file opens with substitutions and missing images. Agree on font and image delivery separately, or send a package.
How to export IDML from InDesign
Exporting IDML step by step
- In InDesign, go to
File › Export - In the format dropdown, choose
InDesign Markup (IDML) - Name the file and save; there are no further options
- Before exporting, check for returns inside sentences. A paragraph return in mid-sentence splits it into two segments in the CAT tool; a forced line break (
Shift+Return) stays in the translation as a tag in the wrong place. Remove both and let the text wrap in its frame. - Also check whether one sentence is split across separate, unthreaded frames. CAT tools treat each story separately, so thread or merge them.
The simplest route is to tick Include IDML in File › Package, so the IDML travels with the INDD, fonts and links. If the package already exists without it, open the INDD from the package folder and export the IDML next to it.
Common mistakes and what they cost
- Sending INDD to a CAT tool user. The translator cannot import it and has to ask for IDML, which costs time and a round of emails.
- Sending a newer INDD to a DTP provider on an older InDesign version. The file will not open, and the provider has to ask for an IDML. Another delay.
- Sending IDML without fonts to a DTP provider doing layout. Everything opens with substitute fonts and the layout looks different. Work stops until the fonts arrive.
- Sending IDML without image links. All linked images show as missing. The DTP provider needs either the original links folder or a packaged INDD. IDML alone is not a complete production package.
- Forgetting to fix hard returns before exporting IDML. Sentences are split across segments in the CAT tool, so the translator sees fragments. Translation quality suffers and the DTP work afterwards grows.
IDML for translation. INDD Package for production. If text needs to move through a CAT tool, IDML goes in. If a human is opening the file in InDesign to do layout work, they need the full package: INDD + links + fonts.
Quick reference: INDD or IDML
| Situation | Format to send | Also include |
|---|---|---|
| Translator using a CAT tool | IDML | A PDF of the source for context |
| DTP provider doing layout (same version) | INDD | InDesign Package (fonts + links) |
| DTP provider (version unknown) | IDML | Fonts folder + links folder |
| Archiving for future use | IDML | Fonts + links separately |
| Translation agency (mixed workflow) | Ask first | Depends on their process |
| Proofreading / review only | Nothing else |
The short version
INDD is the working file; IDML is the exchange format. They serve different steps in the production chain.
If text is going through a CAT tool, export IDML, and remove returns inside sentences before you do. If a DTP provider is doing layout work, package the INDD with links and fonts. If you don't know which version of InDesign they have, IDML is always the safer choice.
Neither format contains the fonts, and images are normally linked, so both travel separately or inside an InDesign package.
Further reading
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