Internationalization for Svelte

Developer-friendly internationalization library for Svelte.

• Bulk dictionary manipulation
• Automatic translation via OpenAI

TL;DR

npm i svintl -D

npx intl hola # initialize dictionaries in default location
npx intl set example.hello "Hello world" # set a translation
npx intl create es # create a new language dictionary

<script lang="ts">
  import { intl, language } from '$lib/intl'

  // bind $language to a dropdown or whatever
</script>

<h1>{@render intl.example.hello()}</h1>

Dictionary format

The dictionary is an object with an arbitrary structure, where strings are located at the leaves.

native: English
example:
  hello: "Hello world"

<h1>{@render intl.example.hello()}</h1>

Values can be specified as JavaScript functions using the following syntax:

example:
  hello: |
    !js
    () => 'Hello world'

This looks weird, suggestions are welcome.

Functions can accept arguments:

example:
  hello: |
    !js
    (count) => `${count || 'No'} item${count === 1 ? '' : 's'}`

<h1>You have {@render intl.example.hello(count)}</h1>

The translation prompt provides clear guidance on using functions across languages to implement phrases with language-specific rules.

Pluralization

For pluralized content, use arrays containing objects with named plural forms. This format automatically generates functions that use Intl.PluralRules for proper pluralization:

items:
  count:
    - one: item
      other: items

product:
  count:
    - one: product
      other: products

For languages with complex pluralization rules (like Russian), include all required forms:

# Russian pluralization
product:
  count:
    - one: товар      # 1, 21, 31, 41...
      few: товара     # 2-4, 22-24, 32-34...
      many: товаров   # 0, 5-20, 25-30...
      other: товаров  # fallback

The array format [{ one: '...', other: '...' }] serves as an indicator for pluralization. The system automatically:

• Detects the array-with-object format
• Generates optimized functions using direct property access
• Eliminates the need for CLDR ordering complexity
• Supports all standard plural categories: zero, one, two, few, many, other

<p>You have {@render intl.items.count(itemCount)}</p>

Context

Translation contexts are automatically saved when using the set command with a comment parameter. These contexts enhance translation accuracy when creating new language dictionaries.

npx intl set app.welcome "Welcome to our application" "greeting shown on homepage"

Contexts are stored in context.yaml alongside your language files:

inputs:
  app:
    welcome:
      input: "Welcome to our application"
      context: "greeting shown on homepage"

When creating new languages with npx intl create <lang>, saved contexts are automatically used to provide more accurate translations by giving the AI translator additional context about how each phrase is used.

CLI

Translations are powered by OpenAI. Ensure you set the OPENAI_API_KEY in your environment variables. .env file is supported.

npx intl

Print help.

npx intl hola

• Create a directory src/lib/intl/ or specifed with -p
• Create en dictionary file with native: English key
• Build dictionaries

npx intl create es
npx intl create en-US
npx intl create pt-BR

Creates a new language dictionary. Language codes must be valid BCP 47 language tags. The new dictionary will automatically include a native key with the language name in that language.

Dictionary names must be valid BCP 47 language tags.

npx intl set example.hello "Hello world"
npx intl set wardrobe.tops "Tops" "Clothing"

Creates a new translation entry with optional context.

npx intl unit items.count "item"

Creates pluralized translation entries for all languages using the object-based format. The system automatically generates appropriate plural forms for each language based on their pluralization rules.

npx intl const example.hello "Hello"

Sets the same value in all dictionaries without translation.

npx intl move example.hello example.greeting.welcome

Moves a translation entry.

npx intl remove example.hello

Removes a translation entry.

npx intl destroy es

Deletes a language dictionary.

npx intl sync en
npx intl sync en example.hello # sync specific key

Syncs (re-translates) all languages using the source language dictionary.

npx intl build

Rebuilds (likely after manual changes).