INDD vs IDML: Which File Should You Send for Translation?
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.
Most clients send the wrong format. Most translators don't know why it matters. And most DTP handoffs involve at least one round-trip email asking for the file to be re-exported. This article removes that round-trip.
What Is an INDD File?
INDD is InDesign's native working format. It stores everything the software uses to render your layout: text frames, linked images, colour swatches, master pages, layer stacking, paragraph styles, object states, interactive elements. It's binary — tightly packed, not human-readable — and it's version-locked.
An INDD file saved in InDesign 2025 cannot be opened in InDesign 2022. No downgrade path exists. If you send an INDD and the DTP provider is on an older version, they can't open it.
INDD is the file you work in day to day. It's not designed for exchange — it's designed for production.
What Is an IDML File?
IDML stands for InDesign Markup Language. It's an open, XML-based interchange format that Adobe introduced in CS4 specifically to solve the version-compatibility problem. An IDML file is actually a ZIP archive containing a set of XML files — one per spread, one for styles, one for fonts, one for 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 — extracting text for translation and reinserting it into the same structure when done.
IDML is version-independent. A file exported from InDesign 2025 as IDML can be opened in InDesign CC 2018 without issue. That's the whole point of the format.
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 (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 | No (linked) | No (linked) |
| Human-readable | No | Yes (XML) |
| Preserves all InDesign features | Yes (fully) | Mostly — some advanced features may differ |
| Package includes links/fonts | Yes (via InDesign Package) | No — must be sent separately |
| 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 is receiving the file and what they're doing with it. Here's how to decide:
Translator / CAT tool
The translator is working in Trados, memoQ, Phrase, or Wordfast. Send IDML — it's the only format these tools can parse. INDD is not supported.
DTP provider on different InDesign version
If you're on InDesign 2025 and they're on 2022, INDD will fail to open. IDML is version-safe. Always export IDML when the provider's version is unknown.
DTP provider doing layout work
If the DTP provider is doing full layout adjustments (not just text swap), send a proper InDesign Package: INDD + all linked images + fonts. IDML alone is not enough for production.
Archive or backup across teams
IDML is a safe archival format — it will open in future InDesign versions without dependency on the exact version it was created in.
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 — requirements vary.
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.
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 adjustments — fixing overset text, adjusting frames, managing 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 doesn't have the fonts installed — or the image links are broken — the file will open with substitutions. Always clarify font and image delivery separately.
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 — no further options are presented
- Before exporting: check for hard returns inside sentences — replace them with soft returns (
Shift+Return). Hard returns split segments incorrectly in CAT tools. - Also check: are any text frames unnecessarily split into separate boxes for the same sentence? CAT tools segment each box independently — merge them if possible.
Export IDML before packaging. If you've already packaged (collected links + fonts into a folder), you can still export IDML from within the package folder — just open the INDD from the package and export alongside it.
Common Mistakes — and What They Cost You
- Sending INDD to a CAT tool user. The translator can't import it. They'll ask for IDML, which costs you at least one day and a confused email chain.
- Sending a newer INDD to a DTP provider on an older InDesign version. The file won't open. No warning — just an error. The provider must ask you to re-export. Another delay.
- Sending IDML without fonts to a DTP provider doing layout. They open the file, everything is substituted. The layout looks completely different. They can't work without the fonts — they'll ask, you'll send, but the project is already behind.
- 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 mid-segment in the CAT tool. The translator sees fragments, not sentences. Translation quality suffers and the DTP fix cost goes up.
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 vs IDML Decision Card
| Situation | Format to send | Also include |
|---|---|---|
| Translator using a CAT tool | IDML | Nothing extra needed |
| 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 | — |
The Short Version
INDD is your working file. IDML is your exchange format. The two are not interchangeable — they serve different steps in the production chain.
If text is going through a CAT tool, export IDML first and fix your hard returns 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 embeds fonts or images. That's a separate delivery, always.
Further Reading
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