# SDLXLIFF

Source: https://traduq.com/glossary/sdlxliff · Updated October 14, 2026

**SDLXLIFF** is the bilingual file format of Trados Studio: an [XLIFF](https://traduq.com/glossary/xliff) 1.2 file with Trados-specific extensions, in which each source segment is stored with its translation, its confirmation status and its match information.

## How SDLXLIFF differs from plain XLIFF

When you add a Word, InDesign or other file to a Trados project, Trados converts it into an SDLXLIFF, so manual.docx becomes manual.docx.sdlxliff. The translation happens in that file.

RWS describes SDLXLIFF as XLIFF 1.2 that uses custom extensions allowed by the XLIFF specification, as memoQ's MQXLIFF and Phrase's MXLIFF also do. Each paragraph is split into segments marked inside the file, and an sdl:seg-defs element stores data that plain XLIFF has no standard place for, such as:

- The confirmation status of each segment: draft, translated, translation rejected or approved, sign-off rejected or signed off
- The match percentage of the translation and its origin, for example a translation memory or machine translation

A tool that doesn't understand these extensions should keep them and work only with the text, which is why SDLXLIFF files usually survive a trip through another CAT tool. Turning the file back into a translated Word or InDesign document is still done in Trados.

## Which tools open SDLXLIFF

- **Trados Studio**, natively
- **memoQ**, which also imports and exports whole Trados packages
- **Wordfast Pro** and **MateCat**, which list SDLXLIFF among their formats
- **Phrase**, which can import it but doesn't recommend it because of possible incompatibilities

SDLXLIFF files usually reach freelancers inside a Trados [project package](https://traduq.com/glossary/project-package). See [how to open an SDLPPX without Trados](https://traduq.com/blog/open-sdlppx-without-trados).

## Example

An agency sends you brochure.idml.sdlxliff because you don't use Trados. You translate it in memoQ and, before delivering, run a QA check that finds a missing tag and a number typed as 1.500 instead of 1,500. You fix both and send the file back. The agency puts it into the target-language folder of their Trados project and generates the translated InDesign brochure.

TraduQ's free tools read SDLXLIFF in the browser, without uploading it: the [QA checker](https://traduq.com/tools/qa-checker), the [converter](https://traduq.com/tools/tmx-converter) to review a file as an Excel sheet, the [TMX editor](https://traduq.com/tools/tmx-editor), which builds a TMX from its segments, and the [word count and quote tool](https://traduq.com/tools/translation-quote).

## Try it

- [Translation QA checker](https://traduq.com/tools/qa-checker) — Check numbers, tags, spaces and consistency in bilingual files.
- [TMX and XLIFF converter](https://traduq.com/tools/tmx-converter) — TMX, XLIFF, SDLXLIFF and PO to Excel or CSV, and back.
- [TMX editor](https://traduq.com/tools/tmx-editor) — Edit target segments with memoQ-style tags, delete units and save a TMX.
- [Word count & quote](https://traduq.com/tools/translation-quote) — Count words by match band against your TM or CAT report, price the job and download the quote PDF.

## Related terms

- [XLIFF](https://traduq.com/glossary/xliff)
- [Project package](https://traduq.com/glossary/project-package)
- [CAT tool](https://traduq.com/glossary/cat-tool)
- [Translation memory](https://traduq.com/glossary/translation-memory)

## Related guides

- [How to Open an SDLPPX (Trados Package) Without Trados](https://traduq.com/blog/open-sdlppx-without-trados) — What's inside a Trados .sdlppx package, how to open and translate it in memoQ, Wordfast Pro, Smartcat or by unzipping it, and when you still need Trados.
- [XLIFF, TMX, and TBX: Translation File Formats Explained](https://traduq.com/blog/xliff-tmx-tbx-formats-explained) — Understand the key file formats used in professional translation, when to use each one, and how they improve your translation workflow.
- [memoQ vs Smartcat vs Wordfast for a Small Agency (2026)](https://traduq.com/blog/memoq-vs-smartcat-vs-wordfast) — memoQ, Smartcat or Wordfast for a small translation agency? 2026 prices, team costs, shared TMs, Trados file support and which fits your agency.