What is the XLIFF file format?
An .xliff file is an open-standard XML document used to exchange translatable content between software localization tools, translation management systems (TMS), and content repositories. XLIFF - XML Localisation Interchange File Format - is maintained by OASIS and is the dominant interchange standard across the professional localization industry.
The format pairs source-language segments with their translations in a structured hierarchy. A <file> element represents one source document; within it, <unit> elements (XLIFF 2.x) or <trans-unit> elements (XLIFF 1.2) each hold <source> and <target> children. Inline codes - <ph> (placeholder), <sc>/<ec> (spanning codes), <pc> (paired codes) - represent formatting tags from the source, allowing translators to place them correctly without exposing raw markup.
XLIFF 1.2 (2008) remains the most widely deployed version despite XLIFF 2.0 introducing a backwards-incompatible redesign in 2014 and XLIFF 2.2 being published in 2024. Many tools export XLIFF with vendor-specific extensions: SDL Trados uses .sdlxliff, memoQ uses .mqxlz. The .xliff extension and its alias .xlf are functionally identical; .xlf is the preferred extension in Apple's Xcode localization workflow.
The srcLang and trgLang attributes on the <xliff> root element declare source and target language using BCP 47 tags (e.g., en-US, de-DE). Related formats include .po (GNU gettext) and .tmx (Translation Memory eXchange).
Security & safety
RISK: LOWPlain XML text file; not executable. No known security issues specific to XLIFF. As with any XML, malformed files may cause parser errors in tools.
Format details
in a nutshellPrograms that open XLIFF files
Windows5 apps
SDL Trados Studio
Paid File → Open → Translation Documents; open the .xliff directly as a translatable project. Supports XLIFF 1.2 and 2.0. 
OmegaT
Open-source Create a new OmegaT project; place the .xliff in the /source folder. OmegaT supports XLIFF 1.2. 
Swordfish Translation Editor
Paid Project → Create Project; add .xliff as a translatable document. Built around XLIFF natively. 
Notepad++ / Visual Studio Code
Open-source Open .xliff as plain XML for inspection; use XML formatter plugin for readability. 
macOS3 apps
Xcode
Free Editor → Export For Localization produces .xliff; import translations via Editor → Import Localizations. Native XLIFF support for iOS/macOS app localization. 
Linux2 apps
Phrase (formerly Memsource)
Freemium Upload .xliff via Projects → Upload Files; supports XLIFF 1.2 and 2.0 for translation in browser. Technical details
deep spec| Standard body | OASIS (Organization for the Advancement of Structured Information Standards) |
| MIME type | application/xliff+xml |
| XML namespace (v2.x) | urn:oasis:names:tc:xliff:document:2.0 |
| XML namespace (v1.2) | urn:oasis:names:tc:xliff:document:1.2 |
| Version history | 1.0 (2002), 1.1 (2003), 1.2 (2008), 2.0 (2014), 2.1 (2018), 2.2 (2024) |
| Most deployed version | XLIFF 1.2 (2008) - dominant in production localization workflows as of 2024 |
| XLIFF 1.2 translation unit | <trans-unit> containing <source> and <target> child elements |
| XLIFF 2.x translation unit | <unit> > <segment> > <source> + <target> |
| Inline code elements | <ph> (placeholder), <sc>/<ec> (spanning codes), <pc> (paired codes) |
| Encoding | UTF-8 required by specification; UTF-16 with BOM also permitted |
| Alias extension | .xlf (functionally identical; preferred by Apple Xcode localization workflow) |
| Vendor extensions | .sdlxliff (SDL Trados), .mqxlz (memoQ, zip-wrapped XLIFF) |
| Language tags | BCP 47 in srcLang and trgLang attributes on root <xliff> element (e.g., en-US, de-DE) |
| Typical size | 10 KB - 50 MB (scales with translatable content volume) |
| Released | 2002 (XLIFF 1.0, OASIS standard) |
| Latest version | XLIFF 2.2 (OASIS, 2024) |
| Open standard | Yes · royalty-free |
| Specification | docs.oasis-open.org |
XLIFF conversions
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