Internationalization (i18n) Tools

Swap between physical and logical properties (margin‑inline vs margin‑left). Live preview with writing‑mode. Internationalize your CSS.

Developer Tools CSS logical properties RTL writing‑mode

Paste the reference language JSON and a target language JSON. See which keys are missing or extra. Translate with confidence.

Developer Tools i18n keys missing translation

Compare width/height with block‑size/inline‑size in different writing modes. Understand intrinsic sizing. Copy best practices.

Developer Tools block‑size CSS inline‑size logical sizing

Display text in horizontal‑tb, vertical‑rl, vertical‑lr. See how block and inline directions switch. For multilingual sites.

Developer Tools CSS text vertical writing‑mode

Paste text with mixed Arabic/Hebrew and English. See the Unicode bidi class of each character and ordering. i18n debugger.

Developer Tools bidi bidirectional RTL text

Explore all Intl APIs: NumberFormat, DateTimeFormat, RelativeTimeFormat, ListFormat. See outputs for any locale. Powerful i18n.

Developer Tools format i18n Intl JavaScript

Test different line‑break and word‑break values on Chinese/Japanese/Korean text. See how browsers wrap. Essential for i18n.

Developer Tools CJK CSS Japanese line‑break

Transform English text into pseudolocalized text with accents, expansion, and brackets. Test your UI's readiness for translation.

Developer Tools i18n pseudo‑localization test translation

Paste your Accept‑Language header and see which languages your site should serve based on quality values. Internationalization helper.

Developer Tools Accept‑Language i18n locale test