ICU MessageFormat Playground
Write ICU MessageFormat patterns with plurals and selects, preview real CLDR output for en, th, ar, ru, and catch syntax errors instantly - client-side.
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What is ICU MessageFormat Playground?
The ICU MessageFormat Playground lets you write and debug locale-aware message strings: type a pattern with plurals or selects, fill the auto-detected variables, and see the formatted output using real CLDR plural rules for English, Thai, Arabic, and Russian. Syntax errors appear instantly from the same parser production i18n stacks use.
Key Benefits
- Test plural and select logic without an i18n setup
- Real CLDR plural categories - Arabic six-form behavior included
- Instant parser-grade syntax errors as you type
- Auto-detected variable fields with number awareness
- RTL-aware preview and everything runs client-side
Common Use Cases
- •Debugging a plural message that misbehaves in one locale
- •Reviewing translator strings before merging them into an app
- •Learning ICU syntax with instant feedback
- •Verifying Arabic and Russian plural forms for a release
- •Drafting next-intl or react-intl messages safely offline
How to Test an ICU Message
- Write or paste the pattern: Start from the plural or select sample, or paste your own ICU pattern.
- Fill the variables: The playground detects every variable automatically - numbers for plural arguments, text for others.
- Switch locales: Preview en, th, ar, or ru to see real plural categories, including Arabic zero/one/two/few/many.
- Fix syntax errors: The parser reports malformed braces or options immediately - correct the pattern until output renders cleanly.
Key Features
- Full ICU parsing: arguments, plurals, selects, and nesting
- Real CLDR plural-rule evaluation for en, th, ar, and ru
- Automatic variable detection with typed input fields
- Instant syntax errors from the production ICU parser
- RTL-aware output preview for Arabic
- Plural and select one-click samples to start from