Unicode CLDR Project


2018-10-15CLDR v34 released
2018-06-20CLDR v33.1 released
2018-03-26 CLDR v33 released

What is CLDR?

The Unicode CLDR provides key building blocks for software to support the world's languages, with the largest and most extensive standard repository of locale data available. This data is used by a wide spectrum of companies for their software internationalization and localization, adapting software to the conventions of different languages for such common software tasks. It includes:
  • Locale-specific patterns for formatting and parsing: dates, times, timezones, numbers and currency values
  • Translations of names: languages, scripts, countries and regions, currencies, eras, months, weekdays, day periods, timezones, cities, and time units
  • Language & script information: characters used; plural cases; gender of lists; capitalization; rules for sorting & searching; writing direction; transliteration rules; rules for spelling out numbers; rules for segmenting text into graphemes, words, and sentences
  • Country information: language usage, currency information, calendar preference and week conventions, and telephone codes
  • Other: ISO & BCP 47 code support (cross mappings, etc.), keyboard layouts

CLDR uses the XML format provided by UTS #35: Unicode Locale Data Markup Language (LDML). LDML is a format used not only for CLDR, but also for general interchange of locale data, such as in Microsoft's .NET.

Who uses CLDR?

Some of the companies and organizations that use CLDR are:

  • Apple (macOS, iOS, watchOS, tvOS, and several applications; Apple Mobile Device Support and iTunes for Windows; …)
  • Google (Web Search, Chrome, Android, Adwords, Google+, Google Maps, Blogger, Google Analytics, …)
  • IBM (DB2, Lotus, Websphere, Tivoli, Rational, AIX, i/OS, z/OS,…)
  • Microsoft (Windows, Office, Visual Studio, …)
        and many others, including:
  • ABAS Software, Adobe, Amazon (Kindle), Amdocs, Apache, Appian, Argonne National Laboratory, Avaya, Babel (Pocoo library), BAE Systems Geospatial eXploitation Products, BEA, BluePhoenix Solutions, BMC Software, Boost, BroadJump, Business Objects, caris, CERN, Debian Linux, Dell, Eclipse, eBay, EMC Corporation, ESRI, Firebird RDBMS, FreeBSD, Gentoo Linux, GroundWork Open Source, GTK+, Harman/Becker Automotive Systems GmbH, HP, Hyperion, Inktomi, Innodata Isogen, Informatica, Intel, Interlogics, IONA, IXOS, Jikes, jQuery, Library of Congress, Mathworks, Mozilla, Netezza, OpenOffice, Oracle (Solaris, Java), Lawson Software, Leica Geosystems GIS & Mapping LLC, Mandrake Linux, OCLC, Perl, Progress Software, Python, QNX, Rogue Wave, SAP, Shutterstock, SIL, SPSS, Software AG, SuSE, Symantec, Teradata (NCR), ToolAware, Trend Micro, Twitter, Virage, webMethods, Wikimedia Foundation (Wikipedia), Wine, WMS Gaming, XyEnterprise, Yahoo!, Yelp

To suggest additions or corrections, please file a ticket.

How to Contribute?

CLDR is a collaborative project, which benefits by having people join and contribute. Anyone can submit data to CLDR, and contribute to making their language usable in a wide variety of products (see Who uses CLDR?). For information on how to set up an account and contribute data, see Survey Tool.

There is a process for resolving conflicting data that depends on voting strength. Members of the Unicode consortium get increased voting strength, from liaison members up to full members. Full members can also participate in the technical committee, which is the ultimate arbiter for the structure and content of CLDR. For information about joining the Unicode Consortium, see Unicode Consortium.

How to Contribute Source Code?

Please see New Developers.

How to Use?

Most developers will use CLDR indirectly, via a set of software libraries, such as ICU, Closure, or TwitterCLDR. These libraries typically compile the CLDR data into a format that is compact and easy for the library to load and use.

For those interested in the source CLDR data, it is available for each release in the XML format specified by LDML. There are also tools that will convert to JSON and POSIX format. For more information, see CLDR Releases/Downloads.


Many people have made significant contributions to CLDR and LDML; see the Acknowledgments page for a full listing.

Regular Semi-Annual Schedule

CLDR has a regular schedule, with two cycles per year. There is a consistent release schedule each year so that implementations can plan ahead. The actual dates for each phase are somewhat adjusted for each release: in particular, the dates will usually fall on Wednesdays, and may change for holidays. 

The two important periods for translators are:
  • Submission: translators are asked to flesh out missing data, and check for consistency.
  • Vetting: translators are asked to review all changed or conflicted values, and reach consensus.
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