XLIFF Translation Files

Format, editors, and workflow for the OASIS standard exchange format.

XLIFF (XML Localization Interchange File Format) is the OASIS standard for exchanging translation data between localization tools. An XLIFF file is plain XML that pairs source text with target text and carries translation metadata — segment IDs, status, comments — so a translation can move between a CAT tool, a TMS, an agency, and your build pipeline without losing context. Multiple versions are in active use: XLIFF 1.2 (most widely supported) and the modern XLIFF 2.x line (2.0, 2.1, and 2.2 — stricter and more modular). Almost every professional translation tool reads and writes XLIFF, which makes it the safest format for moving translations between systems.

Key facts

What it is: XML-based exchange format for translation data
Standard body: OASIS
Versions in use: 1.2 (most common, 2008), 2.0 (2014), 2.1 (2018), 2.2 (2025)
File extension: .xlf or .xliff
Encoding: UTF-8
Used by: CAT tools (Trados, MemoQ, OmegaT), every major TMS, Apple Xcode (until xcstrings replaced it in Xcode 15), translation agencies

What XLIFF is for

XLIFF was designed to solve a specific problem: how do you move a translation project between tools without losing the surrounding metadata? Before XLIFF, every CAT tool and TMS used its own proprietary format, and exporting a project from one system to another usually meant losing translation status, comments, segment IDs, and translation-memory matches.

XLIFF standardizes the carrier file. A translation lives in an XLIFF, and the same XLIFF can flow through a desktop CAT tool, a cloud TMS, a freelance translator's editor, and a QA system without losing any of the metadata that makes the translation reviewable later.

What an XLIFF file looks like

An XLIFF 1.2 file groups translation units inside a <file> element. Each <trans-unit> has a stable id, a <source>, and a <target>:

<xliff xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 http://docs.oasis-open.org/xliff/v1.2/os/xliff-core-1.2-strict.xsd" xmlns="urn:oasis:names:tc:xliff:document:1.2" version="1.2">
  <file original="formats" datatype="plaintext" source-language="en" target-language="de">
    <body>
      <trans-unit id="appName">
        <source>locize.com - localization as a service</source>
        <target>locize.com - Lokalisierung als Service</target>
      </trans-unit>
      <trans-unit id="label.cancel">
        <source>cancel</source>
        <target>abbrechen</target>
      </trans-unit>
      <trans-unit id="label.save">
        <source>save</source>
        <target>speichern</target>
      </trans-unit>
    </body>
  </file>
</xliff>

XLIFF 2.0 introduces a different structure: <unit> wraps one or more <segment> elements, each of which holds the source/target pair. This finer granularity helps tools handle long sentences, paragraph splits, and partial translations more cleanly. Versions 2.1 and 2.2 build on 2.0 with refinements to modules, validation, and metadata handling.

<xliff xmlns="urn:oasis:names:tc:xliff:document:2.0" version="2.0" srcLang="en" trgLang="de">
  <file id="formats">
    <unit id="appName">
      <segment>
        <source>locize.com - localization as a service</source>
        <target>locize.com - Lokalisierung als Service</target>
      </segment>
    </unit>
    <unit id="label.cancel">
      <segment>
        <source>cancel</source>
        <target>abbrechen</target>
      </segment>
    </unit>
    <unit id="label.save">
      <segment>
        <source>save</source>
        <target>speichern</target>
      </segment>
    </unit>
  </file>
</xliff>

XLIFF 1.2 vs 2.x: which version should you use?

For practical interoperability with the widest set of tools today, XLIFF 1.2 is still the safer default. Its structure is simpler, its tooling is more mature, and adoption across CAT tools and TMS systems is universal.

The XLIFF 2.x line (2.0 / 2.1 / 2.2) is the modern standard, with cleaner extensibility and better support for fragment-level metadata. Adoption is still incremental — some agencies and CAT tools accept 2.0 but not 2.1 or 2.2 yet. If you have a choice, ask your translation partner which version they prefer; if you don't, ship 1.2.

Editing XLIFF files

You don't open XLIFF in a text editor for translation work. The XML structure is meant to be processed by tools that show source and target side by side, surface the translation memory, and run quality-assurance checks. Common options:

Desktop CAT tools: SDL Trados Studio, MemoQ, OmegaT (free), Wordfast, CafeTran. Industry standards for freelance translators and agencies.
Cloud TMS platforms: Locize, Phrase, Crowdin, Lokalise, Smartling, Transifex. Same job as desktop CAT tools, but in a browser, with team workflow and CDN delivery built in.
Online editors: translate.i18next.com handles simple cases for free.
Text editors (VS Code, Sublime Text, Notepad++): only for inspection or small fixes. Not suitable for actual translation work.

Common XLIFF workflows

Sending translation work to an agency. Export your source content as XLIFF, send it to the agency, receive the translated XLIFF back, and import it into your build.
Migrating between TMS platforms. Export a project as XLIFF from one system, import it into another. Most TMS-to-TMS migrations use XLIFF as the bridge format.
Apple iOS app localization. Xcode 6–14 used XLIFF as its primary export format. From Xcode 15 onwards, Apple introduced String Catalogs (.xcstrings) as the recommended format, but XLIFF is still supported.
Java / .NET localization. XLIFF is widely used as an interchange format alongside .properties (Java) and .resx (.NET) source files.

How to edit XLIFF files in Locize

Locize is a translation management system designed around the i18next workflow but supporting XLIFF and 14 other file formats end-to-end:

Get started
Import your XLIFF file (1.2, 2.0, 2.1, or 2.2)
Edit translations in the CAT view with translation memory, glossary, and style guide available as context
Use bulk actions for AI / machine translation, then route results through a review workflow
Export back to XLIFF — or convert to JSON, YAML, gettext, .xcstrings, or any of the other supported formats

Frequently asked questions

What is an XLIFF file?

XLIFF (XML Localization Interchange File Format) is an XML-based file format defined by OASIS for exchanging translation data between localization tools. An XLIFF file contains source text in one language paired with target text in another, plus metadata like translation status, comments, and segment IDs. It is the most widely supported format across professional CAT tools and translation management systems.

What is the difference between XLIFF 1.2 and 2.x?

XLIFF 1.2 (released 2008) is the most widely supported version — every major CAT tool reads and writes it. The XLIFF 2.x line — 2.0 (2014), 2.1 (2018), and 2.2 (2025) — is stricter, modular, and better suited to modern workflows, but adoption is incremental. The structures differ: 1.2 uses `<trans-unit>` with `<source>` and `<target>` children; 2.x introduces `<unit>` and `<segment>` for finer-grained segmentation. Most teams still standardize on 1.2 for compatibility; if you have a choice, ask your translation partner which version they prefer.

How do I open an XLIFF file?

XLIFF files are plain XML, so any text editor opens them — VS Code, Sublime Text, or Notepad++ with an XML extension all work. For actual translation work, use a CAT tool (Trados Studio, MemoQ, OmegaT, Wordfast) or a translation management system (Locize, Phrase, Crowdin). These present the source/target pairs in an editor view rather than raw XML.

What CAT tools and TMS support XLIFF?

Every major one. CAT tools: SDL Trados Studio, MemoQ, OmegaT, Wordfast, Smartcat, CafeTran. TMS platforms: Locize (imports and exports XLIFF 1.2, 2.0, 2.1, and 2.2), Phrase, Crowdin, Lokalise, Smartling, Transifex, memoQ Server. Apple Xcode used XLIFF as its primary localization export until xcstrings replaced it as the recommended format in Xcode 15.

Can I convert XLIFF to JSON or other formats?

Yes — most TMS platforms can import XLIFF and export to JSON, CSV, YAML, gettext .po, Android XML, .strings, .xcstrings, and other formats while preserving translations. In Locize, you import an XLIFF, edit translations in the CAT view, and export to whichever format your build pipeline uses. Programmatic conversion is also possible with libraries like `xliff` (Node.js) or `translate-toolkit` (Python).

Is XLIFF still relevant in 2026?

Yes — it remains the standard interchange format for professional localization. Even when teams use newer source formats (JSON, YAML, xcstrings), XLIFF is still the format that flows between CAT tools, agencies, and TMS systems. If you work with external translation agencies or freelancers, expect XLIFF to be part of the workflow.

How do I edit XLIFF files online?

Free online editors like translate.i18next.com handle simple cases. For team workflows with translation memory, glossary, style guide, and review approval, use a translation management system. Locize lets you import an XLIFF, edit it in a CAT-style UI, and export back to XLIFF or any other supported format — without installing desktop software.

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