Attention
TYPO3 v12 has reached end-of-life as of April 30th 2026 and is no longer being maintained. Use the version switcher on the top left of this page to select documentation for a supported version of TYPO3.
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Localization
Except for some low level functions, TYPO3 uses localizable strings for labels displayed in the backend. This means that the whole user interface can be translated. The encoding is strictly UTF-8.
The default language is American (US) English, and the Core ships only with such labels (and so should extensions).
All labels are stored in XLIFF format, generally located in the
Resources/ folder of an extension (old locations
may still be found in some places).
The format, TYPO3 specific details and managing interfaces of XLIFF are outlined in detail in this chapter.