The ICU4X Technical Committee is happy to announce ICU4X 2.1, an update to our modular, portable, and secure i18n library. Important changes since ICU4X 2.0 include: 1. **Latest i18n data**: This release includes an update to CLDR 48. 1. **Calendar improvements**: ICU4X is now being used to implement [Temporal](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Temporal) in V8 and SpiderMonkey. `icu_calendar` has received many fixes and improvements in service of that, including new experimental arithmetic APIs. 1. **Normalizer optimizations**: `icu_normalizer` has received a lot of optimization work, with some more to come. 1. **Collation sort keys**: It is now possible to use `icu_collator` to extract the sort key of a given string to amortize the cost of collation operations. [See the full changelog for more information](https://github.com/unicode-org/icu4x/blob/main/CHANGELOG.md#icu4x-21)

`icu_capi` artifacts based on ref ffi-artifacts/2025-08-13

The ICU4X Technical Committee is happy to announce ICU4X 2.0, a major update to our modular, portable, and secure i18n library. Important changes since ICU4X 1.5 include: 1. **Preference Objects:** Instead of directly passing Locale objects to formatters, most constructors now accept "preference bags." These can be derived from locales but also constructed directly with type-safe enums, and they are more efficient. 2. **Date, Time, and Time Zone Rewrite:** The `icu::datetime` component underwent a complete rewrite with APIs that improve performance and make it easier to do the right thing. The new `icu::time` component replaces `icu::timezone` and handles i18n-focused date, time, and time zone representations. 3. **FFI Overhaul:** C++ namespaces, improvements to function versioning, and idiomatic improvements in all languages, such as getters/setters, iterators, and constructors. 4. **Borrowed variants:** More types have separate owned and borrowed variants, which improves performance. This also enables more components to be compiled without an allocator, making some crates fully `#[no_std]`. 5. **Compiled data updated:** All components ship with the latest versions of CLDR (47.0) and Unicode (16.0). Thanks to everyone who tried the 2.0 Beta releases. We have used your feedback to improve the 2.0 release.

This release includes a lot of the remaining changes slated for 2.0. The major difference from 2.0-beta1 is that it fills in FFI for all new APIs except for those in datetime. This release also brings ICU4X to CLDR 47 Beta 1, ICU 77 RC, and TZDB 2025a. This release is intended to be a stepping stone to the final 2.0 release: we do not expect major changes after this, except potentially to datetime FFI. Clients are encouraged to update to this to experience a smoother 2.0 upgrade. This release includes some breaking changes over 2.0 beta 1. - The `datetime` crate has continued to evolve, with some API renames, though the shape of the crate is mostly the same. - `icu_timezone` has been renamed to `icu_time`, and has been restructured. - Users of `--no-default-features` may find themselves needing to explicitly opt in to an `alloc` feature for some crates, as ICU4X is gaining the ability to be no-alloc. - Many `std` features have been removed from crates that no longer need them. Please refer to [the changelog](https://github.com/unicode-org/icu4x/blob/main/CHANGELOG.md#icu4x-20-beta2) for a full set of differences. Please send feedback by creating an issue or discussion on GitHub.

This release includes a rewritten datetime component, type-safe preferences in all constructors, CLDR 46 and Unicode 16 data, new experimental duration and unit formatting components, an all-new WebAssembly demo, and improvements to many other components including locale tailoring in segmenter, algorithmic plural selection, and IXDTF parsing for zoned datetimes. This release includes breaking changes. The most common you will encounter include: 1. All constructors take a preference bag by value instead of a `&DataLocale`. 2. Many functions had subtle renames, such as `try_from_bytes` becoming `try_from_utf8`. 3. The datetime component was rewritten, and call sites will need to be migrated. Refer to the latest documentation for more information. Please also ask questions on GitHub. This is a beta release, meaning that the team expects this to be mostly compatible with the upcoming 2.0 final release, but there is still room to make changes. Please send feedback by creating an issue or discussion on GitHub.

This release includes CLDR 45 data, new functionality and bug fixes across many components, a full rewrite of `icu_pattern`, and a new consolidated `icu_experimental` crate for features in incubation. As the last 1.x release before 2.0, it includes many new and experimental APIs that will soon become standard in components including `icu_datetime` and `icu_datagen`. See the full [changelog](https://github.com/unicode-org/icu4x/blob/main/CHANGELOG.md#icu4x-15-may-28-2024).

This release includes CLDR 44 and Unicode 15.1 compiled data and datagen support. It also includes a smaller blob provider format, experimental support for plural ranges and rounding increment, and several smaller bug fixes.

This release contains a lot of improvements to ICU4X components pertaining to text engines (bidi, segmentation, properties). It is also the first stable release of `icu_segmenter`. See the full [changelog](https://github.com/unicode-org/icu4x/blob/main/CHANGELOG.md#icu4x-12-apr-13-2023).