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Mastering XLIFF files: How to manage & translate them

software localization
translation management
xliff
developer
Kinga Pomykała
Kinga Pomykała
•Published: December 04, 2025•Last updated: December 04, 2025•5 min read
Mastering XLIFF files: How to manage & translate them

When you step into the world of software localization, sooner or later you encounter XLIFF — the XML-based industry standard for exchanging translation data across platforms and tools. XLIFF files are used in mobile apps, web applications, desktop software, and even enterprise systems because they provide a structured, predictable, and tool-agnostic way to store translations.

In this guide, we'll break down what XLIFF is, why it's so widely used, and how to manage and translate XLIFF files efficiently using SimpleLocalize.

We will focus primarily on the widely adopted XLIFF 1.2 version, as it's the most common in real-world projects and fully supported by SimpleLocalize.

What is XLIFF?

XLIFF (XML Localization Interchange File Format) is a standardized XML format designed to move translation data between systems, developers, and translators.

It exists to solve a simple but common problem:

“How do we exchange translations in a structured way without losing formatting, placeholders, or context?”

XLIFF has become the go-to format for localization due to several key advantages:

  • Tool-agnostic: Most CAT tools, translation management systems, and localization platforms support it
  • Human- and machine-readable: It's XML, so it's structured but still editable
  • Supports metadata: notes, context, developer comments
  • Preserves structure: placeholders, tags, formatting, whitespace
  • Version control friendly: works great in Git and other VCS

While the newer XLIFF 2.0 exists, many platforms, including iOS, SAP, many CAT tools, and several web frameworks, still rely heavily on XLIFF 1.2, which keeps it relevant and widely used.

Inside an XLIFF 1.2 file (structure breakdown)

To understand how translations are stored, let's look at a simple XLIFF 1.2 example:

<?xml version="1.0" encoding="UTF-8"?>
<xliff version="1.2">
  <file source-language="en" target-language="fr" datatype="plaintext" original="Localizable.strings">
    <body>
      <trans-unit id="hello_world">
        <source>Hello World</source>
        <target>Bonjour le monde</target>
        <note>Here is a comment for the translator</note>
      </trans-unit>
      <trans-unit id="items_count">
        <source>You have %d items.</source>
        <target>Vous avez %d articles.</target>
      </trans-unit>
    </body>
  </file>
</xliff>

Key components:

  • <xliff version="1.2">: Specifies the XLIFF version. This post focuses on the 1.2 variant.
  • <file>: Contains metadata such as source and target languages, the original file name and datatype (plaintext, html, xhtml, etc.).
  • <trans-unit>: Represents a single translation entry. Contains:
    • <source> (original text)
    • <target> (translation)
    • <note> (context or translator hint)

This structure is why XLIFF is so useful: it bundles text + translation + context into one clean package.

When should you use XLIFF?

XLIFF (especially 1.2) is ideal when:

  • You work with translation agencies or freelancers. Because XLIFF is widely supported, agencies love it. They can import XLIFF directly into CAT tools like memoQ, SDL Trados, etc.
  • Your app uses placeholders, variables, or rich formatting. XLIFF preserves inline markup safely, something basic file formats like CSV or TXT can break.
  • You want clean version control. XLIFF is text-based, meaning diffs and merges are manageable.
  • You work cross-platform. Many ecosystems use XLIFF: iOS (exports/imports via .xcloc), Angular, Symfony, .NET, Desktop & enterprise apps.
  • You need to exchange translations between different tools. XLIFF acts as a lingua franca for localization data.

And when XLIFF might be “too much”?

If your app has only 20 strings and one extra language, a simple JSON or .strings file might be enough.

But most teams outgrow that quickly, and XLIFF becomes a lifesaver.

Managing XLIFF files with SimpleLocalize

SimpleLocalize fully supports importing and exporting XLIFF 1.2, making it easy to build a clean, automated localization workflow.

What SimpleLocalize can do with XLIFF:

  • Upload your existing .xliff file
  • Edit and translate strings in the translation editor
  • Run quality checks (placeholders, length, missing entries, etc.)
  • Add notes and context for translators
  • Use AI translation or share with human translators
  • Export translations back to XLIFF 1.2 (or any other format you need)
Upload, translate and export XLIFF translation files

You can upload and export XLIFF files directly from the SimpleLocalize translation editor or automate the process using:

Best practices for working with XLIFF files

Here are some tips to keep your workflow smooth:

  • Use stable, descriptive IDs. Avoid using source text as the ID (use welcome_title instead of Welcome to our app!). This prevents issues when source text changes.
  • Add clear context using <note>. Translators work faster and more accurately when they understand usage.
  • Don't remove or modify placeholders manually. XLIFF handles them safely.
  • Keep translation units small. One sentence or UI element per unit is usually ideal.
  • Validate your XLIFF. Especially if you generate it manually or use multiple tools in the pipeline.

Example: Translating an iOS App using XLIFF

iOS apps can export localization data as XLIFF files using Xcode. Here's a quick workflow:

  1. Export .xcloc package from Xcode (contains XLIFF files)
  2. Extract .xliff files from the bundle
  3. Upload XLIFF to SimpleLocalize
  4. Translate or review in the editor
  5. Download updated XLIFF
  6. Re-import into Xcode to update localized strings
  7. Ship the app with updated translations

This is the safest way to work with translation agencies or distributed teams, and avoids painful manual editing of .strings files.

Learn more about iOS translation file formats.

Conclusion

XLIFF is one of the most reliable and flexible ways to exchange translation data in modern software development. With its structured XML format, contextual information, and deep tool support, it has become an industry standard for good reason.

If you're maintaining a mobile app, building a multilingual SaaS product, or collaborating with external translators, SimpleLocalize makes it easy to import, edit, translate, and export XLIFF 1.2 files without headaches.

Get started with XLIFF localization in SimpleLocalize today and see how much simpler managing translations can be!

Kinga Pomykała
Kinga Pomykała
Content creator of SimpleLocalize
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