ICU 79 Released

Unicode® ICU 79 has just been released. ICU is the premier library for software internationalization, used by a wide array of companies and organizations to support the world's languages, implementing both the latest version of the Unicode Standard and of the Unicode locale data (CLDR).

ICU 79 updates to Unicode 18 (blog), including new characters and scripts, emoji, collation & IDNA changes, and corresponding APIs and implementations.

It also updates to CLDR 49 (blog) locale data with many additions and corrections.

Line break backwards-iteration performance has been significantly improved, fixing a long-standing regression.

C++ and Java implementations of the CLDR MessageFormat 2.0 specification have been updated to CLDR 49. Some of the API remains in technology preview.

ICU 79 and CLDR 49 are major releases, including a new version of Unicode and major locale data improvements.

• Details: ICU 79
• Download: releases/tag/release-79.1
• API docs: follow the “Released” links on unicode-org.github.io/icu-docs/
• Maven: com.ibm.icu / icu4j / version 79.1

Attention: Future Changes

• We will phase out cross-version Java serialization compatibility guarantees for ICU4J starting with the ICU 80 release.
• Follow the link for details and other planned changes.

Unicode CLDR 49 Alpha available for testing

The Unicode CLDR 49 Alpha is now available for integration testing.

CLDR provides key building blocks for software to support the world's languages (dates, times, numbers, sort-order, etc.) For example, all major browsers and all modern mobile phones use CLDR for language support. (See Who uses CLDR?)

The alpha has already been integrated into the development versions of ICU and ICU4X. We would especially appreciate feedback from non-ICU consumers of CLDR data on Migration issues. Feedback can be filed using CLDR Tickets.

Some of the most significant changes in this release include the following (for more detail, see the CLDR 49 release note page):

• Updated for Unicode 18 including annotations for the new emoji, new scripts, etc.
• Reflects the most recent updates to external standards and data sources, such as the language subtag registry, UN M49 macro regions, ISO 4217 currencies, etc.
• New formatting options:
• New date & time formatting options including:
• Localized patterns for gluing date & timezoneAppend Items — e.g., Sept 3, EST
• Ordinal days in dates — e.g., Sept 3rd
• Customizing numeric separators for dates and times in patterns: 3-10-2031 → 3/10/2031
• UTC timezone display patterns
• Dual Standard/Daylight format — Sept 3, UTC+3/+2
• Structure for preventing digit-digit merges — e.g., '2026/1/29 GMT-817时'
• Additional skeleton-patterns added for flexible and interval date formats
• Nested bracket replacement — for constructing locale names with parts that have parentheses, e.g., ”birmanês (Mianmar [Birmânia])”
• Additional localized locale display name options - see keys
• New and updated plural and ordinal rules
• New and improved rule-based number formatting (spellout) rules for many new locales
• New units — poundal, dyne, milliinch (US mil)
• Many enhancements of the CLDR specification (LDML) will be in the CLDR 49 Beta (September 23rd).

Locale Coverage Levels

Level	Count	Regional Variants	Usage
Modern	100	399	Suitable for full UI internationalization
Moderate	12	14	Suitable for “document content” internationalization, eg. in spreadsheet
Basic	73	99	Suitable for locale selection, eg. choice of language on mobile phone

This is the second release where the new CLDR Organization process is in place for DDL languages. As a result, several locales were able to reach higher levels or had substantial contributions:

• Adyghe, Kabardian: Adyghe Language and Literature Association
• Laz: Laz Instittue
• Ligurian: Council for Ligurian Linguistic Heritage
• Mara: Mara Language Preservation
• Coptic: St. Shenouda Coptic Society

±	New Level	Locales
📈	Modern	Akan
📈	Moderate	Breton, Coptic
📈	Moderate*	Romansh, Shan, Tigrinya
📈	Basic	Adyghe, Central Kurdish, Colognian, Kabardian, Kikuyu, Kʼicheʼ, Ladin, Prussian, Qʼeqchiʼ, Sunwar (Sunuwar)
📉	Basic*	Tajik, Bashkir, Interlingua, Sardinian, Faroese, Venetian

Note: Each release, the number of items needed for Modern and Moderate increases. So locales without active contributors may drop down in coverage level.

For the details, see the CLDR 49 release note page, which has information on accessing the data, reviewing charts of the changes, and — importantly — will cover Migration issues.

Unicode CLDR 49: Submission open through June 2026

The Unicode® CLDR Survey Tool is open for submission for version 49 through June (see detailed schedule below). CLDR provides key building blocks for software to support the world's languages (dates, times, numbers, sort order, etc.). All major browsers and all modern mobile phones use CLDR for language support. (See Who uses CLDR?)

Via the online Survey Tool, contributors supply data for their languages — data that is widely used to support much of the world’s software. This data is also a factor in determining which languages are supported on mobile phones and computer operating systems.

The new areas in CLDR 49 are focused on:

• Unicode 18 additions: new emoji, script names, …

• Improvements in date and time and locale display names formatting

• New languages available for submission in Survey Tool: Adyghe [ady], Brahui [brh], Hunsrik [hrx],  Interslavic [isv], Kabardian [kbd], Kaitag [xdq], Mara [mrh], and Susu [sus] 

General Submission for TC locales* opened recently and is slated to finish on June 10, 2026. The Survey Tool then enters a vetting phase, where contributors select the best data for each field. That vetting phase is slated to finish on June 29. The draft data will be available in a public alpha in early August, and the final release is targeted for mid-October.

Other locales, managed by the DDL Working Group, have a longer submission period to allow smaller organizations to submit data on a more flexible timeline. The Survey Tool opened earlier for these locales, and will stay in Extended Submission until the end of June, so that these organizations can contribute data for the current release.

Each new locale starts with a small set of Core data, such as a list of characters used in the language. Submitters of those locales need to bring the coverage up to Basic level (very basic basic dates, times, numbers, and endonyms) during the following submission cycle. Once a language reaches Basic coverage, it has the minimum support for use in language selection, such as on mobile devices. In the next submission cycle, the name of that language is also added for translation for all languages at Modern coverage. Locales that reach a higher level of coverage (Moderate or Modern) are suitable for general-purpose support in applications and operating systems.

If you would like to contribute missing data for your language, see Survey Tool Accounts. For more information on contributing to CLDR, see the CLDR Information Hub.

* TC Locales are ones for which major organizations commit to adding data in concert over a short span of time each year.

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