IDML vs INDD: Which InDesign File Format Should You Send for Translation?

If you're preparing an InDesign document for translation, you've probably noticed two file formats in your project folder: the .indd file you've been working in, and the .idml file you exported (or were told to export). They look similar — both open in InDesign, both contain your layout — but they behave very differently when it comes to translation. And which one you send can be the difference between a smooth workflow and a frustrating dead end.

The short answer: send IDML, not INDD. Here's why.

What Is an INDD File?

An INDD file is InDesign's native working format. When you create a new document and press Save, you get an .indd file. It stores everything about your document — layers, paragraph styles, linked images, text frames, master pages, color swatches — in a proprietary binary format that only Adobe InDesign can open.

The word "binary" is the key here. INDD files are not human-readable. Open one in a text editor and you'll see garbage: compressed bytes with no structure you can parse. That's by design — Adobe optimized the format for speed and compactness inside InDesign, not for external access.

The practical consequence: translators and translation tools cannot read INDD files. There is no way to extract text from an INDD file without opening it in InDesign itself. Translation services, CAT tools (SDL Trados, memoQ, Phrase, Déjà Vu), and automated translation platforms — none of them can parse the binary INDD format directly.

What Is an IDML File?

IDML stands for InDesign Markup Language. It is an open, XML-based export format that Adobe introduced specifically to allow external tools to read and modify InDesign documents. When you export via File → Export → Adobe InDesign Markup (IDML), InDesign generates a .idml file: a ZIP archive of structured XML files.

Inside that archive, your document is broken into readable components:

• Stories/ — all the text in your document, one XML file per story thread
• Spreads/ — the page layout and geometry
• MasterSpreads/ — master page definitions
• Resources/ — paragraph styles, character styles, colors, and fonts

Because text lives in standard XML files with clear structure, external tools can open the archive, extract the text, translate it, and put it back — leaving the layout, styles, and frame geometry completely intact.

The practical consequence: every professional translation workflow — CAT tools, translation agencies, automated translation services — is built around IDML. Not INDD.

Why Translation Tools Require IDML

1. Text Extraction

To translate a document, you first need to extract its text into something a translator or translation engine can process. With IDML, extraction is straightforward: open the ZIP, read the Stories/ XML files, pull out the text. With INDD, this is impossible without a running, licensed copy of InDesign.

2. Round-Trip Fidelity

After translation, the translated text needs to go back into the original layout — with every paragraph style, font, and frame position preserved. IDML is designed for this round trip. Translation services modify only the text content in the Stories/ XML files and leave the layout XML untouched. When the translated IDML opens in InDesign, it looks identical to the original — except the words are in the new language.

3. Version Portability

INDD files are version-specific. A document saved in InDesign 2024 cannot be opened in InDesign 2022. IDML files are backward-compatible — a translator using an older version of InDesign can open an IDML from a newer version without issue. This matters when files cross organizations: your team may not run the same InDesign version as your translation partner.

Common Misconceptions

"My translator asked for 'the InDesign file' — doesn't that mean INDD?"

Usually not. When a translator or agency asks for "the InDesign file," they almost always mean the IDML. Some translators with InDesign installed can work directly in INDD, but any translator using a CAT tool needs IDML. When in doubt, send IDML and note the INDD is available if they need it.

"Can't someone just convert INDD to IDML on their end?"

Yes — but only if they have a licensed, running copy of InDesign. If your translator or translation service doesn't have InDesign, they can't do this conversion. You're the one with InDesign open in front of you. The IDML export takes about 20 seconds and saves everyone a time-consuming back-and-forth.

"Will I lose anything by sending IDML instead of INDD?"

No, not for translation purposes. Paragraph styles, character styles, master pages, linked image references, layers — all of it travels through IDML intact. What IDML doesn't preserve are some InDesign-specific features like placed PDFs inside frames, InCopy assignments, and interactive elements (buttons, form fields). For print and translation workflows, none of these typically apply.

How to Export IDML from InDesign

If you haven't exported your IDML yet, it takes three steps:

1. Open your .indd file in Adobe InDesign.
2. Go to File → Export (not Save As — that's INDD only).
3. In the Format dropdown, select Adobe InDesign Markup (IDML), name the file, and click Export.

For a full walkthrough including version-specific tips, see our step-by-step guide to exporting IDML from InDesign.

What to Do with Your IDML File

Once you have the IDML, you have three common paths:

Upload to an automated translation service. TranslateInDesign accepts IDML files directly — upload your file, choose your target language, and receive a translated IDML ready to open in InDesign. Your paragraph styles, fonts, and layout are fully preserved.

Send to a translation agency. Agencies with InDesign experience accept IDML as the standard hand-off format. Pair the IDML with a linked-images package (created via File → Package) if the file uses linked assets the agency will need to see.

Import into a CAT tool. SDL Trados Studio, memoQ, Phrase, and Déjà Vu all support IDML import, enabling translation memory and terminology management. For high-volume or repeat translation projects, this workflow lets you reuse previously translated segments across document versions.

The INDD file stays in your project folder as your working file. The IDML is what you share.

The Rule of Thumb

If you're ever unsure which file to send: send IDML. It is the open, accessible, translation-ready format that every professional translation workflow is built around. INDD is your working file — it stays with you.

Want to see how it works? Upload your IDML file to TranslateInDesign and get a translated layout back in minutes →