Multi-Language Testing Checklist

Supporting multiple languages requires more than translating strings. AI-generated i18n code frequently has missing translations, broken date formats, and layout issues with longer text. This checklist ensures your multi-language support works correctly for users in every locale.

Last updated: 2026-03-14

Translation Completeness

All visible text is translated in every language

Switch to each supported language and navigate every page to verify no untranslated strings appear.

Error messages are translated

Trigger validation errors and server errors in each language and verify the messages appear in the selected language.

Email notifications are translated

Trigger emails while using each language and verify the email content matches the user's selected language.

Dynamic content handles translations correctly

Verify that user-generated content displays correctly alongside translated UI elements without mixing languages.

Layout and Text Rendering

Longer translations do not break layout

Check languages like German or Finnish that often have longer words to verify text does not overflow containers.

RTL layout works correctly for Arabic and Hebrew

Switch to an RTL language and verify the entire layout mirrors appropriately including navigation and forms.

Special characters render correctly

Verify that accented characters, Asian scripts, and other non-ASCII text renders without corruption or missing glyphs.

Font supports all target languages

Check that the chosen fonts include glyphs for all characters needed in every supported language.

Text truncation works across languages

Verify that truncated text with ellipsis works correctly for both LTR and RTL languages.

Locale-Specific Formatting

Dates format according to locale

Verify that date displays use the correct format for each locale, such as DD/MM/YYYY versus MM/DD/YYYY.

Numbers and currencies format correctly

Check that decimal separators, thousand separators, and currency symbols match the selected locale.

Time zones are handled correctly

Verify that times display in the user's local time zone and that time zone conversions are accurate.

Pluralization rules work for each language

Test items that show counts to verify correct pluralization, as rules vary significantly between languages.

Language Switching

Language switcher is accessible on all pages

Verify the language selector is visible and reachable from every page in the application.

Language preference persists across sessions

Select a language, close the browser, reopen it, and verify the app remembers the language choice.

URL structure reflects the language if applicable

Check that language-specific URLs use the correct prefix or subdomain for each language.

Switching languages does not lose page state

Fill a form partially, switch languages, and verify the form data is preserved and the page does not reset.

Frequently Asked Questions

How many languages should I support at launch?

Start with English and your primary target market's language. Adding more languages before validating your product with real users creates maintenance burden. Expand language support based on actual user demand.

Should I use machine translation for initial localization?

Machine translation can provide a starting point, but always have a native speaker review the output. Machine-translated UI text frequently contains awkward phrasing and incorrect technical terminology that damages user trust.

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