Developer support

An important part of the mission of the Internationalization Activity at the W3C is to support developers by sharing advice and reviewing documents. The developers in question mostly include specification writers and browser implementers. (Content developers are mostly catered for by the Education & outreach work we do.)


If you need internationalization advice you can contact us in a couple of ways.

If you want advice on a discussion taking place in the GitHub issue thread of a W3C working group, the best way to alert us is to add the i18n-tracker label to the issue. We'll be notified. If you have a specific question, add it in the thread. This approach is particularly useful since it keeps discussions linked to existing discussion threads, and to appropriate repos.

Alternatively, technical questions can be sent to This is the mailing list of the Internationalization Interest Group.


We are trying to write down as much as we can, so that you don't always need to contact us for information.

The following may be particularly useful:

Spec development techniques

The document Internationalization Best Practices for Spec Developers provides do's and dont's for spec developers, with links to explanations, examples, and useful documents. The information is arranged in a task-oriented way.

The Spec development techniques page provides the same do's and dont's and links, but the information is arranged so that you can quickly drill down to the information that interests you.

I18n Notes and WDs

The Internationalization Activity also published additional documents that provide in-depth coverage of a particular area. You can find a complete set of Technical reports produced by the Activity, but the following list highlights some especially useful ones.

Strings on the Web: Language and Direction Metadata. Describes the best practices for identifying language and base direction for strings that will be used on the Web.

Character Model for the World Wide Web: Fundamentals. Architectural specification providing specification / software developers and content developers with a common reference for interoperable text manipulation on the World Wide Web. Topics addressed include use of the terms 'character', 'encoding' and 'string', a reference processing model, choice and identification of character encodings, character escaping, and string indexing.

Character Model for the World Wide Web: String Matching. Provides authors of specifications, software developers, and content developers a common reference on string identity matching on the World Wide Web. Topics include string identity matching and normalization.

Language Tags and Locale Identifiers for the World Wide Web. Best practices for labelling natural language content and locale preferences in document formats, specifications, and implementations on the Web.

Best Practices for XML Internationalization. A set of guidelines for developing XML documents and schemas that are internationalized properly. Following the best practices describes here allow both the developer of XML applications, as well as the author of XML content to create material in different languages.

Internationalization Tag Set (ITS). Defines data categories and their implementation as a set of elements and attributes called the Internationalization Tag Set (ITS). ITS is designed to be used with HTML5 and schemas to support the internationalization and localization of schemas and documents. An implementation is provided for three schema languages: XML DTD, XML Schema and RELAX NG.

Working with Time Zones. Guidelines for working with time and time zones in applications and document formats. Use cases help developers choose an approach to date and time values that works well with geographically distributed applications. Also provides a vocabulary for talking about time in software, a source of confusion for many developers and content authors on the Web.

Language enablement

Developers who want to better understand language or writing system features, and what must be taken into account to develop internationalized solutions, can find relevant information using the Language Enablement Index.

Other useful resources include the Layout issue tracker, which lists ongoing questions and discussions related to language enablement. Also, the Type Samples library provides pictures of typographic features in the wild.

For more details about the language enablement work of the Activity, see this separate page.


The Internationalization Activity has tests for internationalization features that not only look at whether specs are supported in user agents, but also explore how browsers and other user agents handle regional requirements for language support.

There are two main sets of tests. The i18n test suite conforms to the Web Platform Tests approach, and most of those tests are ported to the WPT repository. There is also a set of Test rigs that can be used in an interactive way to rapidly set up and share tests that explore user-agent support for language-related and spec features; these are particularly useful to support gap-analysis during the language enablement work.


Horizontal review of specifications and documents is a key enabler for the W3C's mission to create a "Web for All". Horizontal reviews look at accessibility, privacy, security, device independence, architecture, and, of course, internationalization.

Working groups wanting to request a review should follow the instructions on the Document Review page.

We strongly recommend that before requesting a review you do a Self-review.

You can see what i18n reviews are in progress by looking at our Review radar, and you can see what issues we are tracking, grouped by spec, using our Review comment tracker or by looking at our Tracker repository on GitHub.