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Mozilla Properties

What are Mozilla Properties files and what do you need to consider before using them for translation?

File Extensions .properties
API Extension mozilla_properties
Import Yes
Export Yes
Pluralization supported? No
Descriptions supported? Yes


Mozilla Localization uses Properties files. Syntaxes and requirements for these properties are mostly identical with standard Java properties files. Therefore, a sanity check prior to translation is often considered a best practice. The sanity check may include removing duplicate keys (especially for larger files) and using correct line breaks (any line break in text strings should be preceded with a “\n”, otherwise it will be ignored by the parser). 

Code Samples

boolean_key = --- true\n
empty_string_translation =
# This is the amazing description for this key!
key_with_description = Check it out\! This key has a description\! (At least in some formats)
key_with_line-break = This translations contains\na line-break.
nested.deeply.key = I'm a deeply nested key.
nested.key = This key is nested inside a namespace.
null_translation =
pluralized_key.one = Only one kitten found.
pluralized_key.other = Wow, you have %s kittens\!
pluralized_key.zero = You have no kitten.
sample_collection = ---\n- first item\n- second item\n- third item\n
simple_key = Simple key, simple message, so simple.
unverified_key = This translation is not yet verified and waits for it. (In some formats we also export this status)