Unicode CLDR Project


What is CLDR?

The Unicode Common Locale Data Repository (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:

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:

        and many others, including:

There are other projects which consume cldr-json directly, see here for a list.

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.

How to Contribute?

CLDR is a collaborative project, which benefits by having people join and contribute. There are multiple ways to contribute to CLDR.

Translations and other language data

CLDR has an online tool to gather data, the Survey Tool. The Survey Tool is open twice a year to gather data for new structure, and make corrections in previously-released data. 

Code and Structure

The CLDR tooling supports the interactive Survey Tool, plus all of the tooling necessary to test and process the release. Programmers interested in contributing to the tooling are welcome; they may also be interested in contributing to ICU, which uses CLDR data. For more information, see http://cldr.unicode.org/development

CLDR covers many different types of data, but not everything. For projects which may cover other types of data, see Other Projects.


People may file tickets with bug fixes or feature requests. Once a ticket is approved, they can also create pull requests on GitHub.

Who has contributed?

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

What is the 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:

The details for the current release are found in Current CLDR Cycle.