# TMX

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

**TMX** (Translation Memory eXchange) is the standard XML format for moving a [translation memory](https://traduq.com/glossary/translation-memory) between CAT tools, storing each translation unit as a source segment and its translations with language codes.

## What is inside a TMX file

A TMX file is plain XML. A header names the tool that created the file and the source language. The body holds the translation units: each one has a variant per language, marked with a language code such as en-US or es-ES, and the text of the segment. A unit can also carry its creation and change dates, the user who created it and custom properties, such as client or project. Inline formatting, such as bold text or a link inside a sentence, is kept as tags.

The format was created by the Localization Industry Standards Association (LISA). Version 1.4b is the one that virtually every [CAT tool](https://traduq.com/glossary/cat-tool) reads and writes.

## TMX and the CAT tool's own format

CAT tools work with their own memory formats, such as Trados's .sdltm or memoQ's internal TMs, and use TMX to import and export them. So TMX is the format you send to a client, receive from an agency, or keep as a backup that does not depend on any vendor. It holds translated segments; bilingual working files are [XLIFF](https://traduq.com/glossary/xliff), and terminology goes in TBX.

## Example

Two agencies send you their memories for the same client, one from Trados and one from memoQ. You export or receive both as TMX, merge them into one file with duplicates removed, check that the language codes match, and import the result into your CAT tool. From then on, every project for that client starts with all of its previous translations.

## Working with TMX files

A TMX file opens in any text editor, but a large one is hard to read that way. TraduQ's free browser tools handle the common jobs without uploading your memory: the [TMX editor](https://traduq.com/tools/tmx-editor) to fix units one by one, the [TMX to Excel converter](https://traduq.com/tools/tmx-converter), [merge](https://traduq.com/tools/tmx-merge) and [split](https://traduq.com/tools/tmx-split), and the [TM cleaner](https://traduq.com/tools/tm-cleaner) for duplicates, empty units and conflicting translations. See [how to merge TMX files](https://traduq.com/blog/merge-tmx-files) and [how to clean a TMX](https://traduq.com/blog/clean-tmx-translation-memory).

## Try it

- [TMX editor](https://traduq.com/tools/tmx-editor) — Edit target segments with memoQ-style tags, delete units and save a TMX.
- [TMX and XLIFF converter](https://traduq.com/tools/tmx-converter) — TMX, XLIFF, SDLXLIFF and PO to Excel or CSV, and back.
- [Merge TMX files](https://traduq.com/tools/tmx-merge) — Combine several TMX files into one, without duplicates.
- [Split a TMX file](https://traduq.com/tools/tmx-split) — One TMX per language pair, year, user, client or size.
- [TM cleaner](https://traduq.com/tools/tm-cleaner) — Find and remove duplicates, empty and broken segments in a TMX.

## Related terms

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

## Related guides

- [How to Merge TMX Files (and Split Them), Free](https://traduq.com/blog/merge-tmx-files) — Combine several TMX translation memories into one without duplicates, or split a big TMX by language, year, user or size. Step by step, in your browser.
- [How AI and RAG Are Changing the Way Translators Work with Large Translation Memories](https://traduq.com/blog/ai-rag-translation-memories) — Explore how AI-powered semantic search and Retrieval-Augmented Generation (RAG) are transforming how translators work with large TMs and multilingual corpora — making millions of segments searchable by meaning, not just word overlap.
- [How to Clean a TMX Translation Memory (Free Tool)](https://traduq.com/blog/clean-tmx-translation-memory) — Remove duplicates, empty and broken units, extra spaces and conflicting translations from a TMX file, step by step, and review every change first.